Question

I saw some code in TCL like this:

namespace eval ::info {
    set count 0;
    set id 1;
    set role admin;

    namespace export *
}



proc ::info::setcount {
    set ::info::count 0;
}

proc ::info::setId {
    set ::info::id 1;
}

proc ::info::setRole {
    set ::info::role user;
}

There are three variables defined in namespace ::info, but that three procs(setcount setId setRole) are not declared in the namespace, seems like they are defined outside of ::info, is this allowed? how does this work?

Answer 1

The procedures are defined in the ::info namespace. They’re just not inside the scope of the namespace eval, a command that just creates the namespace if necessary and then executes the given script within that context. Being executed within the context of a namespace changes how proc places commands that it creates when the names of those commands are not fully-qualified. The namespace exists independently of the namespace eval call.
The variables have to be declared in the namespace though; that avoids some really nasty trouble with resolution of variables that can catch people out.

Personally, I prefer to write code like this:

namespace eval ::foo {
    proc bar ... {
        ...
    }
}

But I know that other people disagree with me. Write what you prefer, as Tcl works just fine with either scheme.