Looking for a cure for weird scope/memory of variables

[Lawrence Velázquez]

On Jul 9, 2013, at 5:19 PM, Joshua Root <jmr at macports.org> wrote:

> On 2013-7-10 03:56 , Clemens Lang wrote:
>> On Tue, Jul 09, 2013 at 07:32:03PM +0200, Gustaf Neumann wrote:
>>> foreach {foo.version foo.string} ${foo.versions} {
>>>    subport foo-${foo.version} [subst {
>>>        pre-fetch {
>>>            system "echo ${foo.version}"
>>>        }
>>>        fetch {}
>>>        extract {}
>>>        use_configure no
>>>        build {}
>>>        destroot {}
>>>    }]
>>> }
>> 
>> I assume there is no sane way to guess what the user wants and somehow
>> integrate this into the subport (and pre-fetch, etc.) procs, is there?
>> 
>> We could have a -subst switch, though:
>>  subport -subst {
>>    code
>>  }
> 
> No need for that; using quotes instead of braces will achieve the same
> thing. The trouble comes of course if you want to substitute some
> variables at definition time and others at runtime (or at the top level
> of the subport but not inside the pre-fetch or other internal
> brace-wrapped string). I guess you could use 'format' on the body.

For selective definition-time substitution, you could use string map (http://wiki.tcl.tk/37332#pagetoc04c6ab3f):

    foreach {foo.version foo.string} ${foo.versions} {
        set script {
            subport foo-${foo.version} {
                pre-fetch {
                    system "echo ${foo.version}"
                }
                fetch {}
                extract {}
                use_configure no
                build {}
                destroot {}
            }
        }
        set script [string map [list \${foo.version} [list ${foo.version}]] $script]
        eval $script
    }

vq