bindall ( ob , fns , options )

API

• ob - Object to bind methods to.
• fns - is an object whose values get fixed bound to ob

optional

• options

  • select - Array of string providing names of functions attached to fns to bind - in case when binding needs to be done selectively.

  • addto - object to bind the newly created bound methods to. Using this option means fns object is not mutated and the original methods attached to fns is kept in place.

  • s - same as select

  • a - same as addto

Install

npm install @sourcevault/bindall

Internals

• reassign .this to fixed object for selected functions

• mutates fns that holds the functions (default behavior) . To prevent mutation use the addto option.

• Other implementation ( lodash, underscore ) of bindall lack options to control what fns is bound to. Also cannot prevent mutation when needed.

Examples

view in beautiful livescript

• . . binding all functions that exists in fns object

bindall = require ("@sourcevault/bindall")

log = function()
{
  console.log (this);
}

// purpose of this excercise is we want access to ob.fuel

ob =
{
  fuel:"coffee",
  fns:
  {
    foo:log
  }
}

ob.fns.foo() // { foo: [Function: log] } // cannot access ob.fuel  :(

bindall(ob,ob.fns) // [WARNING] → will mutate ob.fns

ob.fns.foo() 

// { fuel: 'coffee', fns: { foo: [Function] } } // can access .fuel now :)

• . . for applying to a subset number of functions in fns object

ob = 
{
  fuel:"coffee",
  fns:
  {
    foo:log,
    bar:log
  }
}

// ↓ only ob.fns.bar is bound due to using select option ↓

bindall(ob,ob.fns,(select:["bar"]))

ob.fns.bar()

// { fuel: 'coffee', fns: { foo: [Function: log] , bar: [Function] } }

// ↓ foo is not bound as expected ↓

ob.fns.foo() // {fns: { foo: [Function: log] , bar: [Function] }}

• .. to prevent mutating original object fns

ob = 
{
  fuel:"coffee",
  fns:{
    foo:log,
    bar:log
  }
}

boundfns = bindall(ob , ob.fns , ( select:["bar"], addto:{} ))

// ↓ boundfns contains the newly minted bound fns ↓

boundfns.bar() // { fuel: 'coffee', fns: { log: [Function] , bar: [Function] }}

// ↓ original object unchanged ↓

ob.fns.bar()

// {fns: { foo: [Function: log], bar: [Function: log] } }

Notes on Immutability

If a tree falls in a forest and no one is around to hear it, does it make a sound ?

Passing an {} (empty) object to the addto option makes bindall immutable - in the sense that {} (empty) object is mutated and the original object from which the methods were extracted is untouched.

This is useful . .

• . . if the object providing the methods is external.

• . . when we need to add our bound functions to an independent object of our choosing.

bindall that mutate fns is dangerous and should be used with caution. The main usecase for mutating fns is within the enclave of where it was created.

Updates and API change

• 0.3.0 added s and a for select and addto respectively for power users

• 0.2.0 changed selected to option to expand functionality. Third argument is an object instead of an array and the previous functionality of selected is now passed as value to select key in option. addto allows control of what object to attach thee newly created fuctions to.

• 0.1.0 readme

License

Code and document released under MIT Licence, see LICENSE for details.