Hi Mark! Mark H Weaver <m...@netris.org> skribis:
> l...@gnu.org (Ludovic Courtès) writes: [...] >> Of course. I just meant that, if you can call ‘make-reader’ with >> whatever options you’re interested in, instead of globally changing the >> reader’s option as is currently the case, then you’re halfway through. >> >> And in that case, the reader doesn’t need to be associated with the >> port. Instead, since ‘primitive-load’ honors ‘current-reader’, it just >> needs to be set when loading a file. This way, any changes to the >> reader’s options will be local to that file. > > I see a few problems with that. > > First of all, since the reader directives can be placed anywhere that > comments are permitted, the read options must be changed while the > reader is in the middle of reading a single datum, Yes, but the reader can modify its own options data structure. [...] > In other words, if a program uses 'read' on a data file, the > reader directives '#!fold-case' et al should affect all future calls to > 'read' on that file. Just on that file, or on any file subsequently loaded? > Fluids cannot solve this problem, because the program might be > performing interleaved reads of multiple files within the same thread. SRFI-105 reads: An implementation of this SRFI MUST accept the marker #!curly-infix followed by a whitespace character in its standard datum readers [...] After reading this marker, the reader MUST accept curly-infix expressions in subsequent datums until it reaches an end-of-file [...] To me, this sounds like global reader options (reset on EOF), not like per-port options. >> Concretely, this would mean changing read.c such that each token reader >> takes the reader options as an additional first parameter. Instead of >> looking up the global ‘scm_read_opts’, they would look at this explicit >> parameter. > > This is almost exactly what my patch does. I added an explicit > parameter of type 'scm_t_read_opts *' to most of the helper functions in > read.c, and that parameter is consulted instead of the global options. I like it. > When reader directives such as '#!fold-case' are encountered, both the > 'scm_t_read_opts' struct and the per-port options are mutated. > > 'scm_read' initializes a local 'scm_t_read_opts' struct based on both > the global read options and the per-port overrides (if any), and a > pointer to that struct is passed down to all the helper functions in > read.c that need it. > > What do you think? The patch you posted (“Implement per-port reader options, #!fold-case and #!no-fold-case.”) does all three things at once: (1) explicit instead of global reader options, (2) per-port reader options, and (3) fold-case. Do you think you could split it into 3 patches? I’m happy with (1) and (3). I remain skeptical about (2), because of the mixture of concerns. Sorry for the extra work, but thank you for pushing these things! Ludo’.
