Add support for processing intl.formatMessage when injection is used.

[swernerx]

In our project we had the need to extract from intl.formatMessage as well. According to your documentation this is a feature you do not want to include by default. I perfectly understand the reasoning that it is hard, by any system, to automatically check whether it's the formatMessage injected by react-intl.

In our case we would prefer using formatMessage and life with the risk that some calls might be wrongly analyzed. We just follow the convention that to make it parsable the formatMessage() call has to be called in the intl object. In our application we feel this limitation is pretty safe - and might be for a lot of other uses.

I opened this PR for our team to use and for a general discussion on the topic. Probably we can add a parameter to the plugin to enable this non-safe extraction as well.

What do you think?

[kasparasg]

I'd love to see this merged 👍

[SavageWilliam]

Also need this!

[atomcorp]

Thanks @swernerx! This works a treat!

To the maintainers, our app had something like 1,500 formatMessages, the prospect of converting them to use defineMessage was not appealing. As this person pointed out in 2016 this should be really obvious in the docs. Although preferably this pull request would be merged!

[longlho]

Ack. will review asap

[macca16]

I see this was committed in formatjs/formatjs@b57953e by @longlho

Unfortunately with it being enabled by default it is causing extraction failures in my usage of this.props.intl.formatMessage() as I have numerous usages where I defined localisations e.g.

const translations = defineMessages({
    mystring: {
        id: 'keyname',
        description: 'my desc',
        defaultMessage: 'my english',
    },
});

and used as follows:
this.props.intl.formatMessage(translations.mystring)

Without the suggested option to make this change opt in and no obvious way to opt out of this functionality I needed for now to downgrade babel-plugin-react-intl to 3.0.1

[longlho]

@macca16 can u create an issue in formatjs/formatjs? THanks!