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2c5eeca47a
This allow deferring a variable evaluation to its usage but still benefit from only evaluating it once on multiple uses.
34 lines
1.0 KiB
Makefile
34 lines
1.0 KiB
Makefile
# Utilities to set variables and environment for targets
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# These functions should help replacing immediate evaluation and global 'export'
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# Evaluate a deferred variable only once on its first usage
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# Uses after that will be as if it was an immediate evaluation
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# This can replace using `:=` by default
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#
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# The goal is to use it for `shell` commands
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#
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# variable = $(call memoized,<variable>,<value>)
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#
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# Parameters
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# variable: name of the variable you set
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# value: value that should be set when evaluated
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memoized = $2$(eval $1:=$2)
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# Target specific export the variables for that target
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#
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# target-export-variables <target> <variables>
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#
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# Parameters
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# target: name of target
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# variables: the variables to export
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#
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# The variable will only be evaluated when executing the target as when
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# doing export
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target-export-variables = $(foreach var,$(2),$(call _target-export-variable,$1,$(var)))
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# '$1: export $2' cannot be used alone
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# By using '?=' the variable is evaluated at runtime only
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_target-export-variable = $(eval $1: export $2?=)
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