URL:
<http://savannah.gnu.org/bugs/?47421>
Summary: Add support for doing plugin macro overloading
Project: make
Submitted by: phantal
Submitted on: Tue 15 Mar 2016 04:30:57 PM GMT
Severity: 3 - Normal
Item Group: Enhancement
Status: None
Privacy: Public
Assigned to: None
Open/Closed: Open
Discussion Lock: Any
Component Version: 4.1
Operating System: Any
Fixed Release: None
Triage Status: None
_______________________________________________________
Details:
As a preface: I recognize that what I outline below could be done in other
ways with existing make syntax. I'm not interested in suggestions for
alternative ways to get similar results.
----
I had a situation arise a few weeks ago where I had wanted to be able to do
macro overloading.
I was experimenting with adding support for namespace-scoped variables.
I had originally written it as one function (each namespace was registered to
the same function) but its execution time was rather high. I tested its
expansion time with another macro I wrote for repeatedly expanding expressions
to see the avg/std of the expansion time.
I had thought the problem might be the conditional logic. As a test I broke
it up into separate macros with different names and it improved performance by
an order of magnitude, but it was syntactically awkward because I needed a
separate macro name for listing, setting, and getting as opposed to the more
concise example below.
I'm using C++14 with gnu extensions for my plugin, but the syntax should make
it obvious what I'm doing. Here's a sketch of what I had going:
extern "C" {
#include <gnumake.h>
}
using plugin_function_t = typeof(*gmk_func_ptr());
plugin_function_t namespace_list;
plugin_function_t namespace_add;
plugin_function_t variable_list;
plugin_function_t variable_getter;
plugin_function_t variable_setter;
/*...*/
gmk_add_function( gmk_api::strdup( "namespace" ), namespace_list, 0, 0,
GMK_FUNC_DEFAULT );
gmk_add_function( gmk_api::strdup( "namespace" ), namespace_add, 1, 1,
GMK_FUNC_DEFAULT );
/*...*/
gmk_add_function( gmk_api::strdup( argv[0], variable_list, 0, 0,
GMK_FUNC_DEFAULT );
gmk_add_function( gmk_api::strdup( argv[0], variable_getter, 1, 1,
GMK_FUNC_DEFAULT );
gmk_add_function( gmk_api::strdup( argv[0], variable_setter, 2, 2,
GMK_FUNC_DEFAULT );
... where it could be used like this:
$(namespace asdf)
$(namespace fdsa)
$(asdf name1, value1)
$(asdf name2, value2)
$(asdf name3, value3)
$(fdsa name1, value1)
$(fdsa name2, value2)
$(fdsa name3, value3)
$(info Namespaces: $(namespace ))
$(foreach x,\
$(namespace ) \
, $(foreach y,\
$(${x} ) \
, $(info In namespace ${x}, variable ${y} = $(${x} ${y})) \
))
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