This page is part of the web mail archives of SRFI 6 from before July 7th, 2015. The new archives for SRFI 6 contain all messages, not just those from before July 7th, 2015.
Thanks to Marc Feeley and Per Bothner for responding so quickly. I think that all three interfaces to string ports (SLIB/Kawa/Guile, MacScheme/Chez/MzScheme/Larceny/..., and Gambit) should be SRFIs, but should be separate SRFIs. I thought about submitting the Gambit interface as an SRFI at the same time I submitted SRFI-6, but decided to get some feedback on this one before submitting the other, and I was afraid the SRFI editors might hold both of them up while questioning the rationale for multiple SRFIs on this topic. In fact, the main reason I chose to submit SRFI-6 at this time (when I have a list of about a dozen other SRFIs that I would like to submit) was that I wanted to point out that it is better to have lots of little SRFIs, even if some of them are basically variations of one another, than to merge alternative interfaces into a single large SRFI. I was aware that SLIB provides CALL-WITH-INPUT-STRING and CALL-WITH-OUTPUT-STRING, but I have not used Guile or Kawa and did not realize that they had adopted this interface. The SLIB interface is strictly less powerful than the SRFI-6 and Gambit interfaces, so it is the most portable of the three. In particular, it is easily implemented using either the SRFI-6 or the Gambit interface. As a simple, useful, and highly portable interface, I think the SLIB interface is especially deserving of an SRFI. Although the SRFI-6 and Gambit interfaces are compatible, in the sense that an implementation can easily support both at the same time, they are not interchangeable: Neither interface suffices to implement the other in a straightforward way. The SRFI-6 interface does not provide any way to distinguish string ports from other ports, so a programmer cannot easily redefine CLOSE-INPUT-PORT to return a string of the unread characters when a string port is closed. Similarly the Gambit interface cannot easily emulate code that calls GET-OUTPUT-STRING more than once on the same string port without closing the port. So both SRFI-6 and the Gambit interface provide a feature that the other interface alone cannot easily provide. Most programs do not need either of these features, however. Most programs that use string ports can get along just fine with either the SLIB or the SRFI-6 or the Gambit interface, using SRFI-0 to determine which one is available. That is why I want to propose the SLIB and Gambit interfaces to string ports as separate SRFIs. I do not want to revise SRFI-6 to add the SLIB and Gambit interfaces because, in the short term, I would prefer to have three different SRFIs for string ports, knowing that most major implementations support one of them, than to have a single SRFI that no system supports. In the long run, I would hope that implementations would support the union of these interfaces. I would also encourage implementors to support GET-OUTPUT-STRING-AND-RESET, which returns the string of characters that have been sent to an output string port since it was opened or last reset, and also resets the output string port so it no longer remembers the characters that have been sent to it so far. For example, GET-OUTPUT-STRING-AND-RESET makes it easy to use an output string port as a buffer to connect concurrent threads. Input-output ports, as Marc described, would make this even easier. For optimal benefit in both the short and long term, it seems to me that we should have at least four separate SRFIs for string ports: CALL-WITH-INPUT-STRING and CALL-WITH-OUTPUT-STRING SRFI-6 the Gambit interface CALL-WITH-INPUT-STRING and CALL-WITH-OUTPUT-STRING plus SRFI-6 plus GET-OUTPUT-STRING-AND-RESET plus the behavior of CLOSE-INPUT-PORT and CLOSE-OUTPUT-PORT in Gambit plus input-output strings as described at the end of Marc Feeley's message I would like to submit the first, third, and fourth of these SRFIs in a few days, after giving people a little more time to comment on SRFI-6 so the new SRFIs will benefit from those comments. (Having one person submit all four SRFIs might help to establish that these are alternative interfaces, not competing interfaces. On the other hand, I would be grateful if someone else would save me some of the trouble by submitting one or more of those SRFIs themselves. If you plan to do this, please let me know so we won't be duplicating each other's work.) Will