Hi Paul! On Thu, Jan 11, 2024 at 01:44:19AM -0500, Paul Smith wrote: > I've implemented a new capability for conditional assignments (not > pushed yet). > > After these changes, a "?" can precede any type of assignment > operation, not just "=", and make it conditional (that is, it only > takes effect if the variable is not already set). > > So for example, in addition to "?=" which creates a recursive variable > if the variable is not set yet, GNU Make will support "?:=" which > creates a simple variable if the variable is not set yet.
Thanks!! > Of course if > it's already set then the right-hand side of the assignment is not > expanded. > > Similarly the assignments "?::=" and "?:::=" are also supported. > > > There is one question I wanted to ask for opinions on: what should we > do with the "?+=" operator? There's a use for it: appending to a variable if it wasn't set in the environment (ignoring what happened in the Makefile). Here's what += does: alx@debian:~/tmp$ cat Makefile var ?= foo var += bar $(info $(var)) alx@debian:~/tmp$ make foo bar make: *** No targets. Stop. alx@debian:~/tmp$ make var=foo foo make: *** No targets. Stop. alx@debian:~/tmp$ var=foo make foo bar make: *** No targets. Stop. And here's what ?+= could do: alx@debian:~/tmp$ cat Makefile var ?= foo var ?+= bar $(info $(var)) alx@debian:~/tmp$ make-9000 foo bar make: *** No targets. Stop. alx@debian:~/tmp$ make-9000 var=foo foo make: *** No targets. Stop. alx@debian:~/tmp$ var=foo make-9000 foo make: *** No targets. Stop. In the last case (environment variable), since var was set, ?+= would do nothing, unlike +=. Have a lovely day, Alex -- <https://www.alejandro-colomar.es/> Looking for a remote C programming job at the moment.
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