Purpose: to collect pointers and observations regarding techniques for
reading and writing configuration files by an application

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   * What is a configuration file?

   * What are the issues one needs to keep in mind?

   * What internet resources are available for exploring tcl techniques in writing and reading configuration files? 

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[bach]: lvirden: what I like to do is using arrays. Writing: puts [array] get. Reading read eval array set 

lvirden: That's a pretty common technique. That's why I was surprised not to find a page describing that as well as some of the other techniques (like [option], etc.) 

lvirden: I think that perhaps there are just so many different techniques that we haven't gotten even a small percent of them documented. 

[suchenwi]: But, as I found out, [source] also works on pure data, so you can write:
 array set x [source x.dmp] 

Only you cannot have comments in the data then - or you can, if you accept an array element by the name of #, the , then you can dump

 # {Saved by ... on ...}

But, as I found out, [source] also works on pure data, so you can write:
 array set x [source x.dmp] 

rmax: It's downside is, that this kind of configuration file isn't very readable or editable. 

suchenwi: Oh, you could format it like this:
 foreach i [lsort [array names a]] {
        puts [list $i $a($i)]
 } 

That's actually what I do, so the file still is nice to browse. 

aku [AK]: config files - There was a page about tcl patterns somewhere. I believe this contained something. also look for the pages by [Koen Van Damme] on the wiki.

aku: His homepage refers to a paper by him about parsing data files 

rmax: Hmm, reading and writing configuration files of various flavour seems me
worth spending a tcllib module for. I could add a package that parses windows-style .ini files, I once wrote.

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See [Metakit]

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US: I always use the following code snippet as a configuration preamble.

 if {[string length [info script]]} {
    # It's just a script
    set here [file dirname [info script]]
    } else {
    # Wrapped into an executable
    set here [file dirname [info nameofexecutable]]
    }
 set owd [pwd]
 cd $here
 cd ..
 set CFGDIR [file join [pwd] cfg]
 cd $owd

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