Re: Is string always same as number? (the consistency of lua)

[Christian Tellefsen <christian.tellefsen@...>]

On 2/11/2011 1:47 PM, steve donovan wrote:
> On Fri, Feb 11, 2011 at 2:39 PM, Christian Tellefsen
> <christian.tellefsen@funcom.com>  wrote:
>
> A fair summary. But these two points:
>
> > * It has no type modifiers (like const, for example).
> > * You can't create new types or new complex / compound types.
> We can make a table read-only through some metatable magic, so 'const'
> can be catered for.
>
> And metatables generally give the mechanism to generate _user_ types,
> even if they do all collapse into tables or userdata on the language
> level.
>
> steve d.
I agree. It's a bit of a grey area, I'm not sure if I would consider 
this part of the type system, though you can partially / explicitly 
implement some of the things a "stronger" type system can do.

For example, you can't declare any variable as being const, though you 
can make a table object that can't be changed at all. In this case, Lua 
is "weaker" than, say, the C++ type system is, since you can place fewer 
type constraints in Lua.

The language doesn't do implicit type checks on metatables, though you 
can do it yourself by explicitly typing in a check using getmetatable(). 
In this case, Lua is "weaker" than (for example) C++ classes, in which 
types are automatically checked.

Of course, "weak" and "strong" here isn't saying anything about whether 
the language is "good" or "bad", but rather something about how it 
works, what it is useful for, and how it should be programmed in :D

Cheers,
Christian Tellefsen