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0 pointsgrayrest14y ago0 comments

The optional parens is something I personally go back and forth on. I went through a phase where I always left them off but have been moving back towards using them most of the time. The holdout is for calling things that take functional arguments. Here's how I'd write the nodejs.org home page example:

    {createServer} = require 'http'

    host = '127.0.0.1'
    port = 1337

    server = createServer (req, res) ->
        res.writeHead(200, 'Content-Type': 'text/plain')
        res.end('Hello World\n')
    server.listen(host, port)

    console.log "Server running at http://#{host}:#{port}/"

Notice `require` looks sort of like a language statement. The `console.log` thing is my own quirk. However, the call to `createServer` would require a hanging paren if parens weren't optional. It wouldn't look bad here (and, in fact the official example uses it to chain the listen call) but is less attractive if you're using longer functions. Calls like `memoize` and `operation` (think unit of work pattern) tend to work well with this.

{createServer} = require 'http' host = '127.0.0.1' port = 1337 server = createServer (req, res) -> res.writeHead(200, 'Content-Type': 'text/plain') res.end('Hello World\n') server.listen(host, port) console.log "Server running at http://#{host}:#{port}/"

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4 comments · 2 top-level

shazow14y ago· 2 in thread

Perhaps I'm crazy but I honestly feel mandatory parenthesis here improve readability

    {createServer} = require 'http'
    {createServer} = require('http')

    console.log "Server running at http://#{host}:#{port}/"
    console.log("Server running at http://#{host}:#{port}/")

At the very least, it improves consistency which to me improves readability. Making something "look like language" (or perhaps "prose" is more appropriate) doesn't improve the parsing process for my brain. In fact, the inconsistency with the rest of the non-language "code" throws it off the tracks.

Even if it didn't, I'd still say the ambiguity is not worth it. Perhaps CoffeeScript needs a "use strict"; for the final stroke of irony.

One more question: Why "#{foo}"?

Is there any template language that uses this syntax? (I am not familiar with one.) If it were up to me, I would have chosen "${foo}" to be like Mako, or plain "{foo}" to be like Python's string formatter, or "{{foo}}" to be like the more recently popular Mustache.

Edit: As cschep points out, the "#{foo}" syntax is Ruby string formatting syntax. Thanks.

cschep14y ago

Ruby does string formatting that way.

andypants14y ago

Jade is a templating lib for javascript, and it uses #{var} and !{var}.

(Although I don't know what that would be doing in a console log.)

arckiearc14y ago

I went through the same process as you. I think it's okay not to have hard and fast rules for every acceptable situation to leave off parentheses, it's more a judgement call based on the readability of the statement.

`Require` and `console.log` are perfect examples where leaving off the parentheses helps with clarity, same with the call to `createServer`. In your example I'd even argue that you could do the same with `res.end` too.

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