Question

Many common operations on collections in Julia such as deleting an item from a Set were renamed recently, with the old functions deprecated.

For example,

del(IntSet(1,2,3), 1)

now pops up a warning

WARNING: del is deprecated, use delete! instead.

Some of the renamed functions:

@deprecate  push        push!
@deprecate  pop         pop!
@deprecate  grow        grow!
@deprecate  enqueue     unshift!
@deprecate  unshift     unshift!
@deprecate  shift       shift!
@deprecate  insert      insert!
@deprecate  del         delete!
@deprecate  del_all     empty!

Why were these renamed? Is appending a ! to functions that change the state of a collection now a convention?

Answer 1

You can read the julia-dev thread here. Basically, it’s simply changing to respect the rule described in the arrays documentation:

The last function, fill!, is different in that it modifies an existing
array instead of constructing a new one. As a convention, functions
with this property have names ending with an exclamation point. These
functions are sometimes called “mutating” functions, or “in-place”
functions.

FWIW I think this is a good idea, at least for Base.