NAME
makepp_functions -- Functions in makepp
DESCRIPTION
absolute_filename, "addprefix", "addsuffix", basename, dir, "dir_noslash", filesubst, "filter", "filter_out", "filter_out_dirs", "findfile", "findstring", "find_program", "find_upwards", "find_first_upwards", "first_available", "firstword", if, "iftrue", "infer_linker", "infer_objects", join, make, makemap, makeperl, "map", "mktemp", notdir, only_generated, "only_nontargets", "only_phony_targets", "only_stale", "only_targets", "origin", patsubst, "perl", "phony", "prebuild", "print", relative_filename, "relative_to", shell, "sort", "sorted_dependencies", "sorted_inputs", "stem", "strip", "subst", "suffix", "temporary", wildcard, "word", "wordlist", "words", xargs
Any expression of the format $(name arg1 arg2 arg3)
or $(name)
where name
is not the name of a variable, is interpreted as a function call. The name may contain letters, underscores, or hyphens; to avoid confusion, you may use hyphens or underscores interchangeably, since internally hyphens are converted to underscores. Evaluating such an expression simply invokes a perl subroutine. If name
is preceded by &
it runs the builtin command or script of that name within the makepp process, and returns the standard output.
As for variables you have a choice of $(name ...)
or ${name ...}
. Where the arguments contain these signs, either use the other, or double it as in $((name ...() ))
. Doubling is also useful if you need the arguments to span several lines. The newlines are then treated as spaces, except maybe in define
. There is also the syntax $[name ...]
or $[[name ...]]
, which gets evalutated while reading the makefile, before parsing.
Makepp has a number of builtin functions which may be useful. It supports almost all of GNU make's textual functions (see GNU make's documentation for details), and some of its own. You can define perl subroutines to do whatever you like. See the sub
statement and the section on extending makepp for more details.
File and Filename Functions
- absolute_filename files
-
Converts relative filenames into absolutes. For example,
$(absolute_filename xyz.c)
might return/usr/src/our_project/subdir/xyz.c
. - basename filenames
-
The basename is the entire file name (with the directory), minus the text after the last period. E.g.,
$(basename myfile/version-1.0-module.c)
ismyfile/version-1.0-module
- dir filenames
-
Extracts the directory part of each file in the filename list, including the trailing slash. Returns
./
if there is no directory in the filename. - dir_noslash filename
-
Same as
$(dir )
except that it doesn't return the trailing slash. - filter_out_dirs filenames
-
Returns all filenames that do not refer to directories.
- findfile filename, path
-
Finds a file in the specified path, or in the environment variable PATH if nothing is specified. This can be useful for finding binaries or include files. For example,
TCL_INCLUDE := -I$(dir_noslash $(findfile tcl.h, \ /usr/local/stow/tcl-8.4.5-nothread/include \ /usr/include/tcl8.4 /usr/include/tcl \ /net/na1/tcl8.4a3/include /net/na1/tcl8.4a3/include))
This locates the file tcl.h by searching all of the above directories. The absolute path to the file is returned. Then
$(dir_noslash )
extracts that directory, and it is put into the include path. - find_program name
-
Return the first program in the list that can be found in the PATH. This is useful when there are multiple equivalent programs that may be used, and you just want to pick one of them. For example, here is the default definition of several common variables that makepp supplies if you do not put one in your makefile:
CC = $(find_program gcc egcc pgcc c89 cc) F77 = $(find_program f77 g77 fort77) CXX = $(find_program g++ c++ pg++ cxx CC aCC)
If none of the programs is found,
$(find_program )
returns the first one. This usually won't result in a functional makefile, but it will tend to make for better error messages. For example, if you do something like this:%.o : %.c $(CC) $(inputs) -o $(outputs)
and makepp can't find a C compiler in the list above, it will substitute "gcc" anyway. Otherwise the shell would attempt to execute the source file and the resulting error message might be really strange.
- find_upwards filename
-
Searches for a file of the given name in the directory ., .., ../.., ../../.., etc., until the file is found or the root directory is reached or the directory is located on a different file system. (This last requirement is to prevent problems with automounters or hung network filesystems.)
For example, if you have a project with many levels of subdirectories, you could include this common fragment in all of the makefiles (e.g., by using the
include
statement):TOP_LEVEL_INCLUDE_DIR := $(find_upwards includes) # Searches for a directory that contains the # includes subdirectory. %.o : %.c $(CC) $(CFLAGS) -I$(TOP_LEVEL_INCLUDE_DIR) -c $(input) -o $(output)
Another problem that
find_upwards
can help solve is locating the top-level directory of a build. Often it is useful to define a variable like this:TOP := ../../..
if you have some important information located only in the top-level directory. But this is hard to maintain, because the number of
..
is different for different levels of the directory tree. Instead, you can usefind_upwards
to locate a file which is known to be present only in the top level directory. Suppose, for example, that the fileLICENSE
is located only in the top level directory. Then you could do this:TOP := $(dir_noslash $(find_upwards LICENSE))
$(find_upwards LICENSE)
returns the full path of the license file;$(dir_noslash ...)
strips off the filename, returning only the directory.(Note that the
include
statement automatically searches upwards for files, so there is no need to do something like this:include $(find_upwards top_level_rules.mk)
Instead, you can just do
include top_level_rules.mk
and it will work just as well.)
If the file is not found,
find_upwards
will abort the build with an error message.If you specify more than one file, find_upwards will search for the first one, then the second one, and so on. In other words,
$(find_upwards file1 file2)
is equivalent to
$(find_upwards file1) $(find_upwards file2)
If you want to look for any one of the files, then use
find_first_upwards
instead. - find_first_upwards file1 file2 ...
-
This function behaves like
find_upwards
except that it returns the first file of any files in the list that it finds. Specifically, it checks the current directory for any of the files in the list, and returns the first file which exists or can be built. If none of the files exist or can be built in that directory, it checks .., then ../.., etc., until it reaches either the root directory or a directory which is located on a different file system. - first_available file1 file2 ..
-
Return the first file in a list that exists or can be built. This can be useful for adapting your makefiles to work on several different machines or networks, where important files may be located in different places. For example, here's a line from one of my makefiles:
TCL_LIB = $(first_available \ /usr/local/stow/tcl-8.4.5-nothread/lib/libtcl8.4.so \ /usr/lib/libtcl8.4.so /usr/lib/libtcl.so \ /net/na1/tcl8.4a3/lib/libtcl8.4.a \ /net/na1/tcl8.4a3/lib/libtcl8.4.sl)
This line will check for the Tcl library in all of the above places, stopping at the first one that it finds. The link command then includes $(TCL_LIB) so we get the appropriate Tcl library.
- infer_objects
-
$(infer_objects object1.o object2.o, *.o)
If you use standard conventions regarding header file names, makepp is capable of guessing which
.o
or.lo
files need to be linked with your program. I use this to pick out files from a library directory which contains modules used in many different programs. Instead of making a library.a
file and having the linker pick out the relevant modules, makepp can pick out the relevant modules for you. This way, only the relevant modules get compiled.Makepp's algorithm for inferring object dependencies depends on the convention that the implementation of all classes or functions defined in a header file
xyz.h
are compiled into an object file calledxyz.o
(orxyz.lo
). So makepp's algorithm for inferring object dependencies starts with one or a few objects that we know have to be linked into the program. It looks at which files were included with#include
in those sources, and tries to find corresponding object files for each of the include files.$(infer_objects )
needs to be mentioned in the dependency list of a program, like this:myprog: $(infer_objects main.o another_object.o, \ **/*.o /other/library/dirs/**/*.o) $(CXX) $(inputs) -o $(output) $(LIBS)
The
infer_objects
function takes two arguments (separated by a comma, as shown). The first is one or a few object files that are known to be required (wildcards are permissible here). The second is a list of possible objects (normally you would use a wildcard here) that could be linked in if necessary. The return value from this function is a list that contains first all of the objects in the first argument, and then after those, all additional objects that were contained in the second argument that are required by the objects in the first argument.For example, suppose
main.o
comes frommain.cpp
, which includesmy_class.h
.infer_objects
looks for files with the namemy_class.o
. If exactly one such file is found, it is added to the list. (If two object filesmy_class.o
are found in different directories, a warning message is printed.)infer_objects
also examinesmy_class.cpp
to see what it includes, and what additional object files are implied. - mktemp
- mktemp prefix
- mktemp prefixXXX
- mktemp /
-
Returns an unpredictable temporary filename, which does not currently exist. No name pointing to the same file is returned twice, even with different relative paths, within one makepp run (except possibly with traditional recursive make, or if perl code running within a rule action calls
f_mktemp
). At the end of the makepp run all files returned by this function are deleted, if they exist (again except for those returned by this function in perl code running within a rule).Any number of upper case
X
s at the end of the argument are replaced by that many random letters and digits. The more there are, the less likely this is to collide with other processes, so if you give a prefix like "/tmp/abc.", you should have enoughX
s. If there is more than one X, the first character comes from the process id. If there are none, it is as though there were ten, which is supposedly enough (8.4e17 possibilities or 3.7e15 on Windows). If there is no argument, the prefix defaults to "tmp." in the current directory.Note that you don't want to give such a name as rule targets and dependencies. The result would be correct, but it would be recreated every time you run makepp.
Also, as it is always different, you should use this in a rule action only if you use
:build_check ignore_action
:TMPFILE ;= $(mktemp) # 1 call; "=" would mean 3 calls: 3 files A-count B-count: :build_check ignore_action produce-As-and-Bs >$(TMPFILE) &grep -c /A/ $(TMPFILE) -o A-count &grep -c /B/ $(TMPFILE) -o B-count
Or you should export it and let the Shell evaluate it:
export TMPFILE ;= $(mktemp) A-count B-count: produce-As-and-Bs >$$TMPFILE # makepp doesn't see the var value fgrep -c A $$TMPFILE >A-count fgrep -c B $$TMPFILE >B-count
The last form repeats the previous return value, so you can use it in a pattern rule:
%.x: %.y &grep foo $(input) -o $(mktemp) &sed bar $(mktemp /) -o $(output) # Operate on the output of &grep
- notdir filenames
-
Returns the non-directory portion of the filename(s), i.e., everything after the last slash if there is one, or the whole filename otherwise.
- only_generated filenames
-
Returns only those filenames in the list that were generated by makepp and not since modified, according to the build info file.
This function is useful in clean target rules (though of course
makeppclean
is the preferred variant):$(phony clean): &rm -f $(only_generated **/*)
- only_nontargets filenames
-
Returns only those filenames in the list that are not targets of any rule (either explicit or pattern rules). You may specify a wildcard (see the
$(wildcard )
function for more details on makepp's wildcards). This can be used for generating a distribution target, for example:.PHONY: distribution distribution: &mkdir our_product-$(VERSION) &cp $(filter-out %~, $(only_nontargets *)) our_product-$(VERSION) tar cf - our_product-$(VERSION) | gzip -9c > our_product-$(VERSION).tar.gz
In this case, the
$(only_nontargets *)
returns every file in the current directory that is not a target of some rule. The$(filter_out %~, ...)
removes editor backups.Similar to
only_targets
(see above),only_nontargets
only knows about targets that have been defined already. This is only a problem if you use it to define variables with the:=
assignment; if you use it in the dependency list or in the body of a rule, all other rules will already have been seen. - only_stale filenames
-
Returns only those filenames in the list that were generated by makepp and not since modified, according to the build info file, but are no longer targets of any rule.
This function is useful for ensuring that there are no dependencies on such files, without forcing a clean build of all of the targets:
$(phony flush): &rm -f $(only_stale **/*)
Actually, it's probably better instead to write a script that calls makepp to generate the list of stale files, and then have that script remove all of the listed files that aren't currently under source control, just in case a generated file becomes a source file. Makepp doesn't have such a function built in because makepp is (and probably ought to remain) agnostic about source control.
- only_targets filenames
-
Returns only those filenames in the list that are actually targets of some rule (either explicit or pattern rules). You may specify wildcards (including makepp's special wildcard,
**
) in the filenames. (See the$(wildcard )
function for more details. This can be used for a clean target, for example:.PHONY: clean clean: &rm -f $(only_targets *)
Now if you type
makepp clean
, it will delete everything it knows how to build. But don't create a clean target, usemakeppclean
instead!Another place where it may be useful is to avoid including stale .o files in your build. For example, if you build a library like this:
mylib.a: *.o &rm -f $(output) $(AR) cr $(output) $(inputs)
and then you delete some source files but forget to delete the corresponding .o files, the .o files will still be around. This means they will still be incorporated into the library despite the fact that they are not useful any more. If you modify your rule like this:
mylib.a: $(only_targets *.o) &rm -f $(output) $(AR) cr $(output) $(inputs)
then this problem won't occur.
Note that this refers only to files that are known to be targets at the time you invoke
only-targets
. Ifonly_targets
appears in the dependencies or actions of a rule, then all possible targets will be known because dependencies and actions are not evaluated until the rule is executed. However, if you evaluate try to evaluate it earlier in the makefile with a:=
variable like this:ALL_TARGETS := $(only_targets *) target1: dependency1 actions target2: dependency2 actions
then
only_targets
will not know about the subsequent rules.Similarly,
only_targets
doesn't know about targets produced in makefiles that are loaded with recursive make. (But you shouldn't be using recursive make anyway; use use theload_makefile
statement, or implicit makefile loading instead.) - relative_filename file1 file2 file3
-
Returns the name of those files relative to the current directory (the one the makefile is in). This can also be used to clean unnecessary
./
and other junk from the path:DIR := . SUBDIR := .. FNAME := $(DIR)/../otherdir/$(SUBDIR)/files X := $(relative_filename $(FNAME))
Each result is guaranteed to contain a slash, so that you can use it as an executable name without worrying about the command search path overriding the directory location.
- relative_to file1 file2 file3, directory
-
Returns the name of those files relative to the specified directory. This is typically useful when for whatever reason you have to execute a command from a different directory:
source_backup.tar: cd .. && tar cf $(relative_to $(output), ..) $(relative_to ., ..)
- temporary words
-
Let makepp know that the specified targets may be removed by the rule that generates them. Similar to
phony
, except that makepp expects that a real file of that name will may be affected by the rule. A rule is not executed if only its temporary targets are out-of-date. - wildcard pattern
-
Returns the sorted names of all files matching the given pattern which exist, or those files which do not yet exist but can be built based on the rules that makepp knows about at the point when it evaluates the expression. Ignores files and directories that are not readable.
Makepp supports all the usual shell wildcards (
*
,?
, and[]
). It also has a wildcard**
which matches any number of intervening directories. (This idea was stolen from zsh.) For example,**/*.c
matches all the .c files in the entire source tree.objects/**/*.o
matches all the .o files contained anywhere in the subdirectory objects or any of its subdirectories or any of their subdirectories. The**
wildcard will not follow soft links to directories, nor will it attempt to enter directories which exist but cannot be read. Also files which exist but cannot be read will not be returned by$(wildcard )
.
String Functions
- addprefix prefix, words
-
Prepends the prefix string to each of the words. This is mostly for GNU make compatibility; using rc-style expansion, this can be done in a more readable fashion like this:
MODULES := a b c d X_OLD_STYLE := $(addprefix $(OBJDIR)/, $(addsuffix .o, $(MODULES))) X_NEW_STYLE := $(OBJDIR)/$(MODULES).o # Isn't that easier to read?
- addsuffix suffix, words
-
Appends the suffix string to each of the words. This is mostly for GNU make compatibility; using rc-style expansion, this can be done in a more readable fashion like this:
X_OLD_STYLE := $(addsuffix .o, $(MODULES)) X_NEW_STYLE := $(MODULES).o
- filter patterns, words
-
Returns all words in the list that match the patterns. Patterns may simply be other words, or filename wildcards (i.e.,
*
,?
, and[a-z]
are recognized), or they may have a%
character, which means to match any string at that point (same as*
). - filter_out patterns, words
-
Returns all words in the list that do not match the patterns. Patterns may simply be other words, or filename wildcards (i.e.,
*
,?
, and[a-z]
are recognized), or they may have a%
character, which means to match any string at that point (same as*
).For example:
libproduction.a: $(filter_out test_*, $(wildcard *.o))
will put all .o files which exist or can be built, except those beginning with test_, into libproduction.a.
- findstring find, in
-
Return find, if it is a substring of in.
- firstword words
-
Return the first word.
- if string, result-if-string-not-blank, result-if-string-blank
- iftrue string, result-if-string-true, result-if-string-false
-
An alternative to the
ifeq
, etc., statements. If the string is not blank (i.e., the condition is true), the second argument (the "then" clause) is returned (after variable expansion); if the string is blank, the third argument (the "else" clause) is returned.For example,
CFLAGS := $(if $(filter gcc egcc, $(CC)), -g -Wall, -g)
defines CFLAGS to be
-g -Wall
if the variable CC is eithergcc
oregcc
, and-g
otherwise. (This is what the default build rules do.)iftrue
is similar toif
, except that the string0
is treated as blank. - map words, perlcode
- makemap words, perlcode
-
Similarly to perl's map, applies perlcode to each word in turn and returns the results. The first variant is plain Perl code, while the second variant first passes the perlcode through Make-style variable expansion. The words are expanded in both cases.
The words are in
$_
and are returned unless you undef$_
. This is intended for modifications not easily handled bypatsubst
. Only the first comma is a separator, any others are considered part of the perlcode.# Switch words. Double parens, to allow parens in perlcode, or use ${}: X = $((map $(VALUES), s/(.+)-(.+)/$2-$1/)) # You can use make expressions, but then you must use $$ for perl $: Y = $(makemap $(VALUES), tr/$(OLDCHARS)/$(NEWCHARS)/ or $$_ = 'failed') # You can eliminate candidates: Y = $(map $(VALUES), undef $_ if /no_good/)
- join words1, words2
-
Do a pairwise join of the first words and the second words.
- patsubst pattern, substitute, words
-
Performs a substitution on each word in the word list. A
%
character matches any string. This is best illustrated by an example:OBJS = $(patsubst %.c, object_dir/%.o, $(C_SOURCES))
takes every file in C_SOURCES and returns the name of an object file in object_dir. Sometimes it is more concise to use a substitution reference, e.g., the above could have been written as
OBJS = $(C_SOURCES:%.c=object_dir/%.o)
- sort word1 word2 word3 ...
-
Sorts the words in lexical order and removes duplicates.
Miscellaneous Functions
- prebuild targets
- make targets
-
Returns its argument verbatim, but first builds all the files listed. This is useful when a given file is needed when evaluating a make expression. This typically happens when you have a build where the set of files involved is computed by some shell commands. For example,
file_list : # shell commands to compute a list of files to put into the program my_program : $(&cat $(prebuild file_list))
If you need the list in more than one rule, it would be more efficient to use an expand at most once variable:
file_list ;= $(&cat $(prebuild file_list)) my_program1 : a.o $(file_list) my_program2 : b.o $(file_list)
If instead you specified just
$(&cat file_list)
, then makepp would not force file_list to be up-to-date before it executes the shell command. Using$(prebuild )
is the best way to solve this problem. You might be tempted to try other things, like this:my_program : file_list $(&cat file_list)
but this won't work because
$(&cat file_list)
is evaluated before makepp attempts to buildfile_list
. - only_phony_targets names
-
Returns only those names in the list that are phony targets of some rule (either explicit or pattern rules). You may specify wildcards (including makepp's special wildcard,
**
) in the filenames. (See the$(wildcard )
function for more details. This can be used for grouping targets, for example:$(phony tests): $(only_phony_targets */**/tests)
- perl perlcode
- makeperl perlcode
-
Evaluates perlcode in a block and returns the result. The first variant is plain Perl code, while the second variant first passes the perlcode through Make-style variable expansion.
Note, that, as with all functions, the function delimiter used may not appear within the perlcode outside of single or double quoted strings. But you can double it as in the last example:
VAR = 1 VAR1 = ${perl ($VAR + 1) * 3} VAR2 = $(perl do { $VAR *= 3; return $VAR + 1 } if $VAR) VAR3 = $(makeperl $(VAR1) * 3 + $$VAR) # one Make var and one Perl var VAR = $((perl if( ... ) { ... }))
- phony words
-
Indicates that the list of words are actually phony targets, and returns the list of targets. It's intended to be used like this:
$(phony all): my_program $(phony clean): &rm -f *.o my_program
You can also declare one or more targets as phony with a line like this anywhere in your makefile:
.PHONY: all clean
- print text
-
Outputs the text and returns it. This is mostly useful for debugging, when you don't understand why variable substitution has the result that it does. For example,
XYZ := $(print $(patsubst %.c, %o, $(SOURCE_FILES)))
will print out the result of the
patsubst
call.XYZ := $(patsubst %.c, %o, $(print $(SOURCE_FILES)))
will print out the last argument to the
patsubst
call. - shell shell-command
-
Returns the output from the given shell command, with newlines replaced by spaces.
Note, that, as with all functions, the function delimiter used may not appear within the shell-command outside of single or double quoted strings. But you can double it as in the second example:
date = $(shell date) # better: $(perl scalar localtime) VAR = ${{shell f() { echo hello; }; f}}
- wordlist indexlist, words
- wordlist firstindex, lastindex, words
-
In the first form you supply a list of indices (counting from 1 at the beginning or backwards from -1 at the end) to select the words you want. In the second form you specify the range of words you want returned.
- xargs command list
-
Returns a newline-separated list of commands that each begin with the specified command, and end with as many elements of the list as possible without going over 1000 characters.
The purpose of this is to avoid spilling over the command length limit on your system. For example, if there are a lot of generated files, then you would probably want your clean target (which you should not have, because
makeppclean
is more efficient) to look something like this:$(phony clean): $(xargs $(RM), $(only_targets **/*))
This also has the side-effect that no command whatsoever is generated if the list happens to be empty. But in this case it would be better to use the builtin
&rm
, because the arguments to the builtin commands are only limited by perl's memory:$(phony clean): &rm -f $(only_targets **/*)
If a third argument is specified, then it is used to postfix each command. This is useful for specifying redirectors, e.g. (though here again
&echo
would help):manifest: &rm -f $@ &touch $@ $(xargs echo, $(only_nontargets **/*), >> $@)
makepp also supports many other, less useful functions that GNU make has. See the GNU make documentation for details, because I don't feel like typing it in now. (To my knowledge, the only ones it does not support are call
, error
, and warning
.) These are intended mainly to support existing makefiles; it's very easy to write your own functions in perl, or to use the perl_begin
or sub
statements to manipulate variables directly in perl inside your makefile, so you can do any kind of manipulation if one of these built-in functions isn't adequate.
AUTHOR
Gary Holt (holt-makepp@gholt.net)