TYPO3 Core

My use case is about having additional variables passed in all links (using config.linkVars) that should be taken into account for calculating the cache too. In a specific case, it was a site where we use both language and country to define the content, thus the cache hash needs to take the country into account. For this it is necessary to have cHashes (or hack the Core elsewhere to force it to take the country into account, but using cHashes seems the cleanest way).

You're right that conditions could fit the bill. However in my use case the parameter that we needed to take into account was a country number and the site was available for 186 countries. I can't imagine the cost of using so many TS conditions.

Furthermore I think that this change fits well with the new cHash calculations that were introduced in TYPO3 4.7.

I think it might be "dangerous" to have such a setting which requires lots of knowledge about the caching and hash mechanisms of TYPO3. Once set, it will also add cHash to stuff where we explicitly don't want a cHash (search forms, ...).

Maybe it would be cooler to add a hook to TSFE->getHash() allowing the hook to add parameters to the hash_base which is used to generate the md5 of the cache entry, so that you could add your "country" parameter to the list.

Yes, that could be another possibility. I'm not sure it would help with forms, though, as I'm unsure you could really detect for what usage you are currently generating the link. But you're right it's still probably safer this way.

Ah, ah, interesting, someone already had the same issue (I'm not surprised ;-) ). There's already such a hook in the Core since 4.7, somehow I missed it while investigating cHash creation. I'm going to close this issue as a duplicate.