> On 2019/05/17, at 6:17, Matthew DeVore <matvore@xxxxxxxxxxx> wrote: > > > >> On May 16, 2019, at 8:25 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote: >>> >>> $ git rev-list --filter=tree:2 --filter:blob:limit=32k >> >> Shouldn't the second one say "--filter=blob:limit=32k" (i.e. the >> first colon should be an equal sign)? > > That's right. Fixed locally. > >> >>> Such usage is currently an error, so giving it a meaning is backwards- >>> compatible. >> >> Two minor comments. >> >> If combine means "must satisfy all of these", '+' is probably a poor >> choice (perhaps we want '&' instead). Also, it seems to me that > > I think I agree. & is more intuitive. After I tried this in code, I noticed two problems with & which make me prefer + again: a. the "&" char must be quoted or escaped in the shell, even if it is hugged by alphanumeric characters on either side: $ echo a&b [1] 17083 a -bash: b: command not found [1]+ Done echo a $ b. visually speaking, "&" doesn't stand out very well unless it's surrounded by whitespace, and currently it must *not* be surrounded by whitespace: --filter=combine:blob:none&tree:3&sparse:../foo vs. --filter=combine:blob:none+tree:3+sparse:../foo > >> having to worry about url encoding and parsing encoded data >> correctly and securely would be far more work than simply taking >> multiple command line parameters, accumulating them in a string >> list, and then at the end of command line parsing, building a >> combined filter out of all of them at once (a degenerate case may >> end up attempting to build a combined filter that combines a single >> filter), iow just biting the bullet and do the "potentially be >> improved" step from the beginning. > > My intention actually is to support the repeated flag pretty soon, but I only want to write the code if there's agreement on my current approach. > > My justification for the URL-encoding scheme is: > > 1. The combined filters will eventually have to travel over the wire. > > 2. The Git protocol will either have repeated "filter" lines or it will continue to use a single filter line with an encoding scheme. > > 3. Continuing to use a single filter line seemed the least disruptive considering both this codebase and Git clones like JGit. Other clones will likely fail saying "unknown filter combine:" or something like that until it gets implemented. A paranoid consideration is that clones and proprietary server implementations may currently allow the "filter" line to be silently overridden if it is repeated. > > 4. Assuming we *do* use a single filter line over the wire, it makes sense to allow the user to specify the raw filter line as well as have the more friendly UI of repeating --filter flags. > > 5. If we use repeated "filter" lines over the wire, and later start implementing a more complete DSL for specifying filters (see Mercurial's "revsets") the repeated-filter-line feature in the protocol may end up becoming deprecated and we will end up back-pedaling to allow integration of the "&" operator with whatever new operators we need. > > (I very much doubt I will be the one implementing such a DSL for filters or resets, but I think it's a possibility) > >> So why are we allowing %3A there that does not even have to be >> encoded? Shouldn't it be an error? > > We do have to require the combine operator (& or +) and % be encoded. For other operators, there are three options: > > 1. Allow anything to be encoded. I chose this because it's how I usually think of URL encoding working. For instance, if I go to https://public-inbox.org/git/?q=cod%65+coverage in Chrome, the browser automatically decodes the %65 to an e in the address bar. Safari does not automatically decode, but the server apparently interprets the %65 as an e. I am not really attached to this choice. > > 2. Do not allow or require anything else to be encoded. > > 3. Require encoding of a couple of "reserved" characters that don't appear in filters now, and don't typically appear in UNIX path names. This would allow for expansion later. For instance, "~&%*+|(){}!\" plus the ASCII range [0, 0x20] and single and double quotes - do not allow encoding of anything else. > > 4. Same requirements as 3, but permit encoding of other arbitrary characters. > > I kind of like 3 now that I've thought it out more. > >> >> In any case, I am not quite convinced that we need to complicate the >> parameters with URLencoding, so I'd skip reviewing large part this >> patch that is about "decoding". > > It's fine if we drop the encoding scheme. I intentionally tried to limit the amount of work I stacked on top of it until I got agreement. Please let me know if anything I've said changes your perspective. > >> >> Once the combined filter definition is built in-core, the code that >> evaluates the intersection of all conditions seems to be written >> sanely to me. > > Great! I actually did simplify it a bit since I sent the first roll-up. > > Thanks. >
