I'd like to use namespaces as one would in javascript by using the keyword "with", but CoffeeScript reports this as a reserved keyword and refuses to pile is there any way I could use namespaces in cs?
In particular, I want to include a CoffeeScript file dynamically (trusted source), like loading models for a database schema, but I want the included script to have access to a local namespace.
Edit:
Here's what I want to do. I am setting up a web framework that maps the directory tree to an application based on express and mongoose. For example, there's a sub-directory 'models' that contains a file 'user.coffee' with code like this inside:
name:
type: String
unique: on
profiles: [ Profile ]
Whereby Profile is a class that sits in a local object named model. When the user model is being loaded, I wanted it to access the model classes that sit in my local model store.
My work-around for now was to write model.Profile into the file 'user.coffee'. Hope it is clear what I mean.
2nd Edit
Here's how I did it without using with:
user.coffee
name:
type: String
unique: on
profiles: [ @profile ]
profile.coffee
content: String
And here's how it's dynamically loaded:
for fm in fs.readdirSync "#{base}/models"
m = path.basename fm, '.coffee'
schema[m] = (()->
new Schema coffee.eval (
fs.readFileSync "#{base}/models/#{fm}", 'utf8'
), bare: on
).call model
mongoose.model m, schema[m]
model[m] = mongoose.model m
Seems an okay solution to me.
I'd like to use namespaces as one would in javascript by using the keyword "with", but CoffeeScript reports this as a reserved keyword and refuses to pile is there any way I could use namespaces in cs?
In particular, I want to include a CoffeeScript file dynamically (trusted source), like loading models for a database schema, but I want the included script to have access to a local namespace.
Edit:
Here's what I want to do. I am setting up a web framework that maps the directory tree to an application based on express and mongoose. For example, there's a sub-directory 'models' that contains a file 'user.coffee' with code like this inside:
name:
type: String
unique: on
profiles: [ Profile ]
Whereby Profile is a class that sits in a local object named model. When the user model is being loaded, I wanted it to access the model classes that sit in my local model store.
My work-around for now was to write model.Profile into the file 'user.coffee'. Hope it is clear what I mean.
2nd Edit
Here's how I did it without using with:
user.coffee
name:
type: String
unique: on
profiles: [ @profile ]
profile.coffee
content: String
And here's how it's dynamically loaded:
for fm in fs.readdirSync "#{base}/models"
m = path.basename fm, '.coffee'
schema[m] = (()->
new Schema coffee.eval (
fs.readFileSync "#{base}/models/#{fm}", 'utf8'
), bare: on
).call model
mongoose.model m, schema[m]
model[m] = mongoose.model m
Seems an okay solution to me.
Share Improve this question edited Jun 15, 2011 at 18:04 Johann Philipp Strathausen asked Jun 15, 2011 at 15:12 Johann Philipp StrathausenJohann Philipp Strathausen 5,7364 gold badges32 silver badges39 bronze badges 5-
I'm afraid your edit hasn't made your intentions much clearer. Could you add representative code for
model.Profileand how you would like to use it? – lawnsea Commented Jun 15, 2011 at 15:54 -
Stick an
@in front ofProfilewhen defining it:class @Profile. Sincethisisglobal, that'll make it a global namedProfile. No changes needed touser.coffee(though you could write@Profileto make it clearer that you're referencing a global). – Trevor Burnham Commented Jun 15, 2011 at 16:02 -
Profile is a mongoose Schema, and it is defined dynamically the same way User is: via a CoffeeScript file. profile.coffee in this case. See github./LearnBoost/mongoose and mongoosejs. - so I cannot define it globally. Despite that, I wanted to avoid global definitions. However, I'll give the @ a try - it's a synonym for
thisin CoffeeScript, right? – Johann Philipp Strathausen Commented Jun 15, 2011 at 17:05 -
Well, if
@piles tothis, I couldn't use it in other functions, like callbacks, since it would refer to that function... – Johann Philipp Strathausen Commented Jun 15, 2011 at 17:11 -
By the way, I now consider using
coffee.evalnot such a good idea. Instead, one could just userequirethat will resolve coffe-script files as well. – Johann Philipp Strathausen Commented Aug 29, 2011 at 10:14
4 Answers
Reset to default 6Having someone else's opinion forced on you? It's Hack Time™!
o =
a: 1
b: 2
c: 3
`with(o) {//`
alert a
`}`
"Compiles" to:
var o;
o = {
a: 1,
b: 2,
c: 3
};
with(o) {//;
alert(a);
};
It's a pity that this is another area where Doug Crockford's opinion is taken as gospel. with Statement Considered Harmful rejects it on the basis of ambiguity of property writes, but ignores its usefulness when used with a read-only context object, such as a context object which defines a DSL-like API.
The Coco fork of CoffeeScript supports a with syntax; see https://github./satyr/coco/wiki/additions. However, that syntax simply sets the value of this to the target object in a block, rather than piling to the problematic and deprecated with keyword.
Let's say that you wanted to emulate Coco's with syntax in CoffeeScript. You'd do something like this:
withObj = (obj, func) -> func.call obj
Then you could write
withObj = (obj, func) -> func.call obj
withObj annoyingly.lengthy.obj.reference, ->
@foo = 'bar'
@bar = 'baz'
Of course, in such simple cases, it's better to use a utility function like jQuery or Underscore's extend:
_.extend annoyingly.lengthy.obj.reference, foo: 'bar', bar: 'baz'
No. However, you can use destructuring assignment to achieve a similar effect.
{foo, bar, baz} = require 'toocoollib'
foo 'whoa!'
You should also be aware that the with keyword is deprecated and is a syntax error in ES5 strict mode. The consensus among mainstream JS hackers is that with is a bad idea.
If you posted an example of what you would like to do, I could give a more specific answer.
Just found that on the CoffeeScript FAQ page about "Variable Importing":
https://github./jashkenas/coffee-script/wiki/FAQ
It seems, that the use of this technique is discouraged in CoffeeScript and not supported.