Dynamically generate new named class from string with coffeescript

Question

I have looked around and have found a number of questions which approach using-a-string-to-define-the-class-name and dynamic-class-generation-in-coffeescript> but neither of them exactly address my problem, so I am wondering whether I making some fundamental mistake in my approach to the problem.

In the loop below I am looping through some data parsed from JSON. For each set of data I want to extend my class Robot with string = new Robot where string is a string.

Currently my code does not produce any errors, and successfully creates new Robots but since their name is a string, trying to access them with robot1.move() or robot2.doSomeOtherClassyThing() does not work and tells me they are undefined.

This seems like it should not require a verbose helper function to make it work. What am I missing here?

 createRobots: -> # process robot commands
        createXcoord = missionData.xCoord
        createYcoord = missionData.yCoord
        createOrient = missionData.orientation
        createInstru = missionData.robotInstructions
        for command in createOrient
          robot = 'robot' + (_i + 1)
          name = robot
          robot = new Robot \ # create named Robot 
            name
          , createXcoord[_i] 
          , createYcoord[_i] 
          , createOrient[_i] 
          , createInstru[_i]
          console.log(robot)

I think what is happening is that the variable "robot = 'string' is written over when the robot = new Robot is declared.

The outcome I am hoping for is string1 = new Robot, "string2 = new Robot". Does that make sense? jsfiddle.net/7EN5y/1

Brigand · Accepted Answer · 2013-05-19 22:19:46Z

2

You need to add them to a context. If you want them to be global, create a variable like this:

# Either the browser root, or the CommonJS (e.g. Node) module root
root = window or exports

If you want an object that holds robots, add such an object to the root.

root.robots = []

Then when creating robots, add them to such an object.

robot = 'robot' + (_i + 1)
name = robot
robot = new Robot # ...
root[name] = robot # or robots[name] = robot

You may then use code like robot1.move(), or robots.robot1.move() (depending on if you attached them to the root or not).

answered May 19, 2013 at 22:19

Brigand

86.4k20 gold badges167 silver badges174 bronze badges

Sign up to request clarification or add additional context in comments.

8 Comments

mu is too short Over a year ago

But then you'd need to know the names elsewhere in order to access them as root[name]. I think something along the lines of root.robots = { } is the only sane way to proceed.

happilyUnStuck Over a year ago

Sorry I marked your answer as accepted and then not. It helps in so much as it fixes a scope issue I had, but does not actually seem to address the question I asked.

happilyUnStuck Over a year ago

I think what is happening is that the variable "robot = 'string' is written over when the new Robot is declared. The outcome I am hoping for is string = new Robot. Does that make sense? jsfiddle.net/7EN5y/1

Brigand Over a year ago

I guess I don't really understand what you're trying to accomplish. What is the purpose of the line should = 'shouldnt'?

Brigand Over a year ago

@happilyUnStuck, this is my best attempt at understanding what you want.

|

Collectives™ on Stack Overflow

Dynamically generate new named class from string with coffeescript

1 Answer 1

8 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

8 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related