[Tcl-bugs] [ tcl-Feature Requests-1880980 ] Option to [glob] to ease recursive traversal

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Feature Requests item #1880980, was opened at 2008-01-28 17:12
Message generated for change (Comment added) made by evil_son
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Category: 35. Pathname Management
Group: None
Status: Open
Resolution: None
Priority: 5
Private: No
Submitted By: Evil Son (evil_son)
Assigned to: Vince Darley (vincentdarley)
Summary: Option to [glob] to ease recursive traversal

Initial Comment:

Currently,  to traverse a directory hierarchy: in the top directory we need to explicitly glob for all directory entries (including those that start with a period) and then filter out "." and ".." and so on recursively for children directories

The following suggested option to [glob] will simplify code as well as provide some speed increase.

[glob -walk] will return all directory entries in the current dir including those that start with a period _except_ for "." and ".."  i.e it filters out the current and parent directories.  Other filters can be stacked on top of it as per usual with [glob]

This option does _not_ walk the entire directory tree recursively.  As such the name "-walk" may be considered misleading.

[glob -walk] essentially provides a filter to a previously suggested option [glob -all]: request id 1880967 at http://sourceforge.net/tracker/index.php?func=detail&aid=1880967&group_id=10894&atid=360894
and may well be used more often than [glob -all] raising doubts about the need for the latter.

Checking for recursive links in the filesystem is still the responsibility of the user.

e.g usage. To print the names of all and only directories under $root:

proc rec-print-dirs {dir} {
  puts $dir
  foreach d [glob -walk -directory $dir -types {d}] {
    rec-print-dirs $d
  }
}
rec-print-dirs $root

Thank you
E Wilson


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>Comment By: Evil Son (evil_son)
Date: 2008-02-01 02:01

Message:
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Originator: YES

Following up on my previous post: what if glob -walk returned a list of
pairs <filename, type (i.e. file or dir)> of all directory entries except
for . and ..

So to print out files under a directory (without error checking or
checking for empty return lists):

proc allfiles {dir} {
  foreach pair [glob -walk -directory $dir] {
  foreach {entry type} $pair {break}
  if {$type eq "d"} { allfiles $entry }
  elseif {$type eq "f"} { puts $entry } 
  }
}
allfiles someDir


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Comment By: Evil Son (evil_son)
Date: 2008-01-29 03:37

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In response to sender "nobody",
if -all were not to return "." and ".." then it would behave exactly like
-walk.  My less specific (compared to yours) version of -all was aimed at
generality while the more specific -walk (which you call -all) is the one
I'd use more often .. like you and perhaps most users.

Since the existing options are strong enough and we can easily wrap Tcl
procedures around them, the motivation is really performance ... which
raises the question is there a better interface that can provide superior
performance.  I think there is but it may become too specific to directory
traversal and will require more work; so I hesitated suggesting it.  I will
put up another request in a couple of days describing it.

Thanks for your comment


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Comment By: Nobody/Anonymous (nobody)
Date: 2008-01-28 18:11

Message:
Logged In: NO 

I think -all is a good idea provided that it does not return . and ..

Given that, -walk would be equivalent to -all -types d, and thus
redundant.


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