| Message ID | 32d9759c21dfe0792ff0.1399822726@argentina |
|---|---|
| State | Superseded |
| Headers | show |
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@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), $$(filter-out), etc. > +# These rules ensure that these variables and functions are only expanded during > +# the $(eval) step, and not earlier. Otherwise, unintuitive and undesired > +# behavior occurs with respect to these variables and functions. > +# > ################################################################################ > > define inner-generic-package
Hi Yann, On Sun, May 11, 2014 at 10:42 PM, Yann E. MORIN <yann.morin.1998@free.fr> wrote: > Thomas, All, > > On 2014-05-11 17:38 +0200, Thomas De Schampheleire spake thusly: >> As the rules with respect to variable and function references and the need >> for single or double dollar signs are not trivial, add a comment in >> pkg-generic.mk describing them. >> >> Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com> >> >> --- >> package/pkg-generic.mk | 13 +++++++++++++ >> 1 files changed, 13 insertions(+), 0 deletions(-) >> >> diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk >> --- a/package/pkg-generic.mk >> +++ b/package/pkg-generic.mk >> @@ -250,6 +250,19 @@ endif >> # argument 3 is the uppercase package name, without the HOST_ prefix >> # for host packages >> # argument 4 is the type (target or host) >> +# >> +# Note about variable and function references: inside all blocks that are >> +# evaluated with $(eval), which includes all 'inner-xxx-package' blocks, > > Here I'd say something like: > > ... evaluated with $(eval) [either directly or indirectly], ... > > We want these rules to apply even to functions called from inside an > evaluated function, right? > No, I don't think this is true. The big problem is that most functions can be called both within as outside of an evaluated block. When it is not evaluated, then the double dollar signs cause incorrect behavior. Take the following test program (which you can play with to test out different combinations) FOO = bar func = something-$(FOO)-$(1) define block ▸‐‐‐‐‐‐‐X = $(1) ▸‐‐‐‐‐‐‐Y = $$(FOO) target: ▸‐‐‐‐‐‐‐@echo X=$$(X) Y=$$(Y) Z=$(call func,else) endef all: ▸‐‐‐‐‐‐‐@echo Z=$(call func,else) $(eval $(call block,hello)) If you change 'func' to use $$(FOO) instead of $(FOO), then the 'all' target will have output /bin/sh: 1: FOO: not found Z=something--else instead of Z=something-bar-else Best regards, Thomas
diff --git a/package/pkg-generic.mk b/package/pkg-generic.mk --- a/package/pkg-generic.mk +++ b/package/pkg-generic.mk @@ -250,6 +250,19 @@ endif # argument 3 is the uppercase package name, without the HOST_ prefix # for host packages # argument 4 is the type (target or host) +# +# Note about variable and function references: inside all blocks that are +# evaluated with $(eval), which includes all 'inner-xxx-package' blocks, +# specific rules apply with respect to variable and function references. +# Numbered variables (parameters to the block) can be referenced with a single +# dollar sign: $(1), $(2), $(3), etc. All other variables should be referenced +# with a double dollar sign: $$(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
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@gmail.com> --- package/pkg-generic.mk | 13 +++++++++++++ 1 files changed, 13 insertions(+), 0 deletions(-)