Re: [Boost-build] prototyping alternative Boost.Build syntax

Subject: Re: [Boost-build] prototyping alternative Boost.Build syntax
From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2016-10-29 16:10:37

AMDG

On 10/29/2016 01:45 PM, Stefan Seefeld wrote:
> 
> Cool, that worked ! Can you outline what the four calls do ?
> 
>     bjam_interface.define_action("gcc.compile", "g++ -c -o $(<) $(>)",
> [], 0)
>     bjam_interface.call("gcc.compile", "hello.o", "hello.cpp")
>     bjam_interface.call("UPDATE_NOW", "hello.o")
>     bjam_interface.call("UPDATE")
> 
> from my guess:
> 
> * the first line defines an action

Yes.

> * the second line defines a rule by which "hello.o" is made from
> "hello.cpp" using that action

Yes.

> * the third line requests "hello.o" to be remade ("now" - is that a
> blocking call ?)

Yes.

> * not sure about the fourth line
> 

It clears the update list causing the default
update phase to do nothing.

There's actually one more component that's missing:

bjam_interface.call("DEPENDS", "hello.o", "hello.cpp");

gcc.compile doesn't automatically set up this
dependency.  (The first time you build it will
update because hello.o is missing.  However,
without DEPENDS, touching hello.cpp won't cause
hello.o to update.)

In Christ,
Steven Watanabe