Export Readers for TypeScript

[benk-lastyard]

Hi,

The main reason behind this pull request is that I would like to extend one of the barcode readers to create a custom barcode reader of my own. The problem I had is that quagga.d.ts doesn't export the reader class that I need to extend.

This pull request adds all of the reader classes to quagga.d.ts. In doing so I have also made these other changes

• Added the protected access modifier to most functions in the reader classes that have an underscore prefix. This seemed to be the original intent however without the access modifier they would all be public. Since these classes were not exported previously there should be no usages outside of this project so the change seems safe to me.
• Added typescript return type to functions where they were missing.
• Renamed BarcodeReader._decode to BarcodeReader.decode. This is because the EANReader attempts to call that function for each of the supplementary readers so the decode function cannot be protected.

[rollingversions]

Change Log for @ericblade/quagga2 (1.3.0 → 1.4.0)

New Features

• Export reader classes.

Edit changelog

[ericblade]

hi @benk-lastyard thanks for the pull request! I'll take a quick look at it

[benk-lastyard]

Awesome!

[ericblade]

@benk-lastyard i really do appreciate the typescript updates! When I went through and converted the readers all over to typescript i tried to do a lot of cleanups like that, but obviously i missed some things.

Let me ask you this -- what would you think of adding an index.ts to src/reader, which imports the individual readers, and then exports them, like the first part of the change 1a89e5d#diff-eea04ce1ae4f8822f870f8d3ac9534c16295a179248987b68f7f58eef30d739b

then we only need a single import added to quagga.js, like

import * as Readers from './reader/index';

and then follow that up with

export { 
   ....,
    Readers,
    ....,
}

so if you're extending the reader from external code, you would do something like

import { Readers } from '@ericblade/quagga2';
class MyReader extends Readers.EANReader {
....
}

would that work?

Also, please add yourself to Contributors in package.json, if you'd like credit beyond the github repo!

[benk-lastyard]

@ericblade No problem with your suggestion. I am far from a Typescript master but I'll try and follow your suggested code snippets above and see how far I get.

Should I move BarcodeReader

quagga2/src/quagga.js

Line 143 in 0b3e3b1

BarcodeReader,

to the new location as well? What is the risk of breaking any code in the wild?

I'll make a start on the suggested changes in the meantime.

[ericblade]

@benk-lastyard Good idea, i was thinking of that, too. I'm not aware of anyone actively using that, so I'm not incredibly worried about it breaking any thing people are actually using, so let's go ahead and move that (and if anyone does complain, I can just reissue it as v2.0.0, which i'll need to do anyway when i remove official node 10 support, which i just made a todo issue for)

TypeScript is mostly great! I've loved using it, but I'm no master at it either!

[benk-lastyard]

Hi @ericblade,

Are you able to offer any guidance on how I would update quagga.d.ts in order to export the Readers namespace so that it can be used like so

import { Readers } from '@ericblade/quagga2';
class MyReader extends Readers.EANReader {
....
}

I have tried export interface Readers, export type Readers and export class Readers but as expected none of them seem to be correct because it isn't an interface, type or class!

reader/index.ts looks like so

import BarcodeReader from './barcode_reader';
import TwoOfFiveReader from './2of5_reader';
import NewCodabarReader from './codabar_reader';
import Code128Reader from './code_128_reader';
import Code32Reader from './code_32_reader';
import Code39Reader from './code_39_reader';
import Code39VINReader from './code_39_vin_reader';
import Code93Reader from './code_93_reader';
import EAN2Reader from './ean_2_reader';
import EAN5Reader from './ean_5_reader';
import EAN8Reader from './ean_8_reader';
import EANReader from './ean_reader';
import I2of5Reader from './i2of5_reader';
import UPCEReader from './upc_e_reader';
import UPCReader from './upc_reader';

export {
    BarcodeReader,
    TwoOfFiveReader,
    NewCodabarReader,
    Code128Reader,
    Code32Reader,
    Code39Reader,
    Code39VINReader,
    Code93Reader,
    EAN2Reader,
    EAN5Reader,
    EAN8Reader,
    EANReader,
    I2of5Reader,
    UPCEReader,
    UPCReader,    
}

[benk-lastyard]

Hi @ericblade

The code has been updated based on your feedback here

Regards

[ericblade]

LGTM :) Thank you!

[benk-lastyard]

Thanks @ericblade