TCL : Regarding source , package , namespace comma

Question

I want to know about modular programming in tcl and how we can achieve that .

In some tcl tutorials mention like source command having some drawbacks in achieving "modularity" so that we came to the "package" after that "package" is having some more drawbacks so that we came with the combination of package and namespaces .

I want to know what are the drawbacks and proper hierarchy of 3 concepts . Can Anyone help me ?

Answer 1

I'm not sure if I understand your question correctly, so I'll try to explain the 3 commands you throwed in your question:

• source: Evaluates a file as a Tcl script. - It simply opens the file, reads until the EOF character (^Z on both windows and *nix) and evaluates it.
  It does not keep track of sourced files, so you can source the same file again (great for hotpatching), but this is the drawback: It will source the file again.
• package: Manages packages. It basically keeps track of the provided packages and tries to figure out which file it has to source to load a new package.
• namespace: They provide context for commands and variables, so you don't have to worry about unique names for your commands. Just the namespace has to be unique. Has nothing to do with loading packages or other modules, it just provides namespaces.

I suggest that you use packages, each package in it's own file, each package with a namespace equal to the package name where all commands reside.
You should export the public commands with namespace export.