'''package names'''

Returns a list of the names of all packages in the interpreter for which a version has been provided (via '''[package provide]''') or for which a '''[package ifneeded]''' script is available. The order of elements in the list is arbitrary.

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'''package names''' will only deliver all available packages if it has searched all package indices before. To force this, do a dummy '''[package require]''' before:

 catch {package require nonexistentName}
 package names

'''[DGP]''' - To be more precise, [[package names]] returns a list of all the package names that are already known to the [[package]] command. That is not the same as all the names that could become known by operation of the [[package unknown]] callback.

The default [[package unknown]] callback is [[tclPkgUnknown]] and it is that default callback that exhibits the behavior described above -- after one run, all installed package names are known. The [[package unknown]] interface does not require that behavior, and other callbacks may not (IMHO, should not) implement it.

[Lars H]: Feeling slightly Cantorian, I'd propose the following for a foolproof (never loading a package, even if it's got a bizarre name) method of listing all package names:
  proc all_package_names {} {
     set res ""
     while {$res ne [set res [package names]]} {
	if {[package unknown] eq ""} then {break}
	uplevel #0 [package unknown] [list $res+1 ""]
     }
     return $res
  }
The idea is that "[[package names]]+1" cannot be the name of a package known to the package database, so telling [package unknown] to search for it will force some additional data to be entered (even with a very lazy package unknown handler) as long as there is any.

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[LV] 2008 Jun 05
Did something change with the way package names, etc. worked in Tcl 8.5? The reason I ask is this. Under Tcl 8.4, when I ran this routine, I would get over 400 names returning in [ActiveTcl]. Under ActiveTcl 8.5, I am only seeing 100. Now, I know that ActiveTcl, out of the box, comes with fewer packages. But what I am seeing is different. For instance, most of the tcllib packages are displaying differently now. I have tcllib installed in both local teapots. I can start up both tclsh's , do a package require math::bigfloat and get it.

However, the above code, when run against tcl 8.4.19, shows all the math::bigfloat, etc. routines, but when run against activetcl 8.5.2, the routine only shows math, with none of the ::other names. They are there in AT 8.5 - just not showing up. Even at the top level - things like md5 shows when I run the above code in AT 8.4 but not AT 8.5.

It seems as if somehow things are just not quite the same. 

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See also:

   * [package]
   * [package provide]
   * [package require]
   * [package unknown]
   * [package versions]

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