Re: elseifs and the fact that assignmens are not expressions

[Sam Roberts <sroberts@...>]

On Wed, Jan 24, 2007 at 09:17:35AM +0100, Flemming Madsen wrote:

I have the impression that there is some resistance to making ALL
statements into expressions on the part of the lua team. I thing it has
to do with the simplicity of the parser, or some ambiguity in the
syntax.

I'd be interested in knowing what exactly the resistance is, because I
too would like write code as you present it below! It seems simple,
consitent, predictable, comfortable to use. Btw, "&&" is not an operator
in lua, you have to use the english word.

Why is a statement/expression duality necessary in lua? What are some
examples of where it would introduce confusion?

Sam


> local s,e,c,r,line,file,modified,pid,running
> local fd = io.popen("sh -c 'vi -r 2>&1'", "r")
> 
> while (line = fd:read("*line")) do
>       ^^^^^^
>    if s,e,c = string.find(line, "^ *file name: ([%w%p]*)") then
>       ^^^^^^^^
>        file = c
>    elseif s,e,c = string.find(line, "^ *modified: (%a*)") then
>           ^^^^^^^^
>        modified = c ~= "no"
>    elseif s,e,c,r = string.find(line, "^ *process ID: (%d*)(.*)") then
>           ^^^^^^^^^
>        pid = c
>        running = string.find(r, "(still running)", 1, true) ~= nil
> 
>        if file && modified then
>            io.write(string.format("%d %8d%s %s", modified and 1 or 0,
>                                   pid, running and "*" or " ", file)
>        end
>        file = nil
>        running = nil
>    end
> end
> fd:close()
> 
> 
> Obviously this will not work, since assignments are not expressions in lua,
> nor is there any way of embedding assignment in expressions
> 
> Is there an easy way around this that i missed. Is this even a candidate 
> for the FAQ
> 
> 
> Best /Flemming*
> *