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77 lines
1.6 KiB
77 lines
1.6 KiB
makeerror [](http://travis-ci.org/nshah/nodejs-makeerror) |
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========= |
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A library to make errors. |
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Basics |
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------ |
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Makes an Error constructor function with the signature below. All arguments are |
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optional, and if the first argument is not a `String`, it will be assumed to be |
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`data`: |
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```javascript |
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function(message, data) |
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``` |
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You'll typically do something like: |
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```javascript |
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var makeError = require('makeerror') |
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var UnknownFileTypeError = makeError( |
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'UnknownFileTypeError', |
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'The specified type is not known.' |
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) |
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var er = UnknownFileTypeError() |
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``` |
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`er` will have a prototype chain that ensures: |
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```javascript |
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er instanceof UnknownFileTypeError |
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er instanceof Error |
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``` |
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Templatized Error Messages |
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-------------------------- |
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There is support for simple string substitutions like: |
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```javascript |
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var makeError = require('makeerror') |
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var UnknownFileTypeError = makeError( |
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'UnknownFileTypeError', |
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'The specified type "{type}" is not known.' |
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) |
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var er = UnknownFileTypeError({ type: 'bmp' }) |
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``` |
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Now `er.message` or `er.toString()` will return `'The specified type "bmp" is |
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not known.'`. |
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Prototype Hierarchies |
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--------------------- |
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You can create simple hierarchies as well using the `prototype` chain: |
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```javascript |
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var makeError = require('makeerror') |
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var ParentError = makeError('ParentError') |
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var ChildError = makeError( |
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'ChildError', |
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'The child error.', |
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{ proto: ParentError() } |
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) |
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var er = ChildError() |
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``` |
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`er` will have a prototype chain that ensures: |
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```javascript |
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er instanceof ChildError |
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er instanceof ParentError |
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er instanceof Error |
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```
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