[Buildroot] [PATCH 2 of 7] infra: add comment describing single/double dollar-sign rules
Yann E. MORIN
yann.morin.1998 at free.fr
Sun May 11 20:42:01 UTC 2014
Thomas, All,
On 2014-05-11 17:38 +0200, Thomas De Schampheleire spake thusly:
> As the rules with respect to variable and function references and the need
> for single or double dollar signs are not trivial, add a comment in
> pkg-generic.mk describing them.
>
> Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire at gmail.com>
>
> ---
> package/pkg-generic.mk | 13 +++++++++++++
> 1 files changed, 13 insertions(+), 0 deletions(-)
>
> diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk
> --- a/package/pkg-generic.mk
> +++ b/package/pkg-generic.mk
> @@ -250,6 +250,19 @@ endif
> # argument 3 is the uppercase package name, without the HOST_ prefix
> # for host packages
> # argument 4 is the type (target or host)
> +#
> +# Note about variable and function references: inside all blocks that are
> +# evaluated with $(eval), which includes all 'inner-xxx-package' blocks,
Here I'd say something like:
... evaluated with $(eval) [either directly or indirectly], ...
We want these rules to apply even to functions called from inside an
evaluated function, right?
Regards,
Yann E. MORIN.
> +# specific rules apply with respect to variable and function references.
> +# Numbered variables (parameters to the block) can be referenced with a single
> +# dollar sign: $(1), $(2), $(3), etc. All other variables should be referenced
> +# with a double dollar sign: $$(TARGET_DIR), $$($(2)_VERSION), etc. Also all
> +# make functions should be referenced with a double dollar sign: $$(subst),
> +# $$(call), $$(filter-out), etc.
> +# These rules ensure that these variables and functions are only expanded during
> +# the $(eval) step, and not earlier. Otherwise, unintuitive and undesired
> +# behavior occurs with respect to these variables and functions.
> +#
> ################################################################################
>
> define inner-generic-package
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