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Re: Ideas of a new version of PostScript (called "Computer PostScript")

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On 2024-03-07, news@zzo38computer.org.invalid <news@zzo38computer.org.invalid> wrote:
> I had ideas how to improve PostScript programming language, making a new
> version, which can be called "Computer PostScript" since it is meant for
> computers rather than printers. It is based on level 3 PostScript, and some
> of the extensions provided by Ghostscript, and some of my own new stuff.
>
> * Add append operator of NeWS, which concatenates two strings or arrays.
> Also add arrayop operator of NeWS, which is receiving a procedure and two
> arrays (or strings) of equal length and produces a single array from
> combining the corresponding elements of each one with the same index by
> the specified procedure. (This could also be worked with dictionaries too,
> I suppose; if the dictionaries have the same keys.)
>
> * Add straccum and strfinish operators. (I have implemented these in
> PostScript itself, but may be more efficient as native operators.) The
> straccum operator will make a writable file object, which remembers
> anything written to it; strfinish takes the file object from straccum on
> the stack, and closes it and then the output is a new string object that
> contains all data that was written to the file before it was closed.
>
> * Remove the /PageCount system parameter, which is only relevant for
> printers and not for computers. However, the /PageCount page device
> parameter of Ghostscript is included.
>
> * The job server is also not needed so it can be removed, too.
>
> * Possibility of having alpha transparency, in the current colour and in
> raster images. There might also be operators for adding layers to a layer
> stack, and then you can combine modes when popping the layer stack. (Some
> page devices might not support alpha transparency in the output, and some
> vector devices might not allow alpha transparency at all.)
>
> * The ARGUMENTS array of Ghostscript is included. In "program mode" (which
> is the default mode), this is always used for command-line arguments. (If
> the system's character encoding is a superset of ASCII then they should be
> passed unchanged to the PostScript program. This is required to be the same
> character encoding used for file names, but is allowed to be any ASCII
> based encoding as long as it satisfies this requirement.)
>
> * Some operators that require an existing allocation can now automatically
> allocate a string or array if you pass null. For example: copy, readline,
> cvs, and some others. Some, such as readstring, might accept a number in
> place of a string to automatic allocation.
>
> * Add a built-in procedure called #! which skips the rest of the current
> line of the input file. (Store this is systemdict.)
>
> * An option (perhaps a user parameter) to display error messages on stderr
> while not redirecting any other output (e.g. print = == etc) to stderr.
> (Perhaps it should be the default setting, or even the only setting.)
>
> * Type 4 function dictionaries, like PDF.
>
> * Possibility to set a font list and character encoding separately. (If
> you use the existing way to set the font, it is set to a font list
> containing a single font, and the encoding of that font.)
>
> * Allow glyphshow to use numbers even for fonts that are not CID fonts
> (names can still be used, too).
>
> * Add a page device parameter that can be retrieved and used when setting
> it to preserve the existing device state for that specific page device,
> including not erasing the page. This parameter is mutually exclusive with
> some of the other parameters, though.
>
> * Similarly than the above, you can save the graphics state with a page
> device, enter a new one, and then when you go back, you can continue with
> the existing page. (See below for why this is relevant.)
>
> * Add a command to select a internal raster page device which stores the
> picture in a buffer which can then be read back after you pop that internal
> device off of the stack. This is similar than "makeimagedevice" command in
> Ghostscript, but I dislike some of the details of Ghostscript's working.
>
> * Add a Environment resource category which allows reading and writing
> environment variables.
>
> * Add the %pipe% device of Ghostscript, but without input buffering. (The
> input buffering makes many things difficult. Ghostscript does not have this
> problem when reading from stdin, but %pipe% still has that problem.)
>
> * The %pipe% device may also be opened in (r+) mode for two-way
> communication with an external program, like in FreeBSD.
>
> * Possibly some way to define animations.
>
> * Make a C API for defining your own operators and for extending the
> PostScript interpreter with dynamically linked C codes. This C API would
> also be usable for defining page devices as well. For vector devices, you
> can also access the glyph names and CIDs of text (or you can choose to
> ignore text and just have the PostScript engine to convert them to the
> shapes), and pdfmark can also be implemented by any page devices.
>
> * A variant of Type 1 fonts but unencrypted.
>
> * Make the "known" operator to work with strings and arrays as well as
> with dictionaries. Also add "knownget" operator.
>
> * Make the fileposition operator to work with non-positionable files
> too in which case it tells the number of bytes read or written; with
> seekable files it works like it already normally does.
>
> * Add "kforall", "vforall", and "kvforall", usable with any types that
> "forall" is usable with; they will give you only the keys, only values,
> or both keys and values, respectively. (For dictionaries, forall is the
> same as kvforall; for strings and arrays, forall is same as vforall.)
>
> * Add a "unread" operator, similar than the "ungetc" function of C.
>
> * I don't like the exception for storing local objects in systemdict,
> so I would propose an alternative: You can store references to local
> objects inside of global objects if those local objects were created
> before the first time "save" is executed.
>
> * The copypage operator works like level 2 PostScript, although it might
> not be available for all devices on all implementations. (If it is not
> available, then it is an error when used in that way.)
>
> * Colour management: Ghostscript uses colour management unless you set
> the UseFastColor mode. I think it should not do that, and should just use
> direct colours normally. However, you can add a /ColorManagement page
> device parameter; if 0 then there is no colour management, if 1 then there
> is colour management if using managed colour spaces (such as ManagedRGB,
> ManagedCMYK, etc instead of DeviceRGB, etc) and you can set the rendering
> intent separately at different times, if 2 then the colour management is
> done only during post processing, if 3 then it is like 1 but uses the
> colour management in all colour spaces including Device colour spaces, and
> 4 means that colour management is applied afterward during postprocessing.
> (Some settings might be unavailable for some output devices. For most
> output file formats, colour management should be disabled by default
> (unlike Ghostscript), although it may be enabled by command-line argument
> or within the PostScript program itself.) (The CIE-based colour spaces
> remain available and are managed in the way that they are specified by
> level 3 PostScript. Also, even if colour management is set to 0, such
> things as transfer functions will still work (although they would normally
> only be set for printer drivers and such things and not for most output
> file formats); the /ColorManagement parameter only controls use of managed
> colour profiles, similar than /UseFastColor in Ghostscript.)
>
> * Add a DeviceRaw colour space, allowing to access raw colour data of the
> specific output device (usually an integer or a string) (in some cases,
> e.g. PDF, this might not be available).
>
> * An extension of the PostScript binary object sequence format to support
> 64-bit integers, 64-bit floating point, and dictionaries.
>
> * New filters: ExternalDecode and ExternalEncode, which use an external
> program. ExternalEncode will write anything written to the filter file to
> the external program's stdin, and whatever the external program writes to
> its stdout will be written to whatever the filter is writing to; the
> ExternalDecode is other way around.
>
> * New filters named ByteTranslateEncode and ByteTranslateDecode, which
> work like those in Ghostscript.
>
> * Allow the dictionary for ASCII85Encode and ASCIIHexEncode to specify
> where line breaking should occur (including none at all) and to be able
> to suppress the final > or ~> when the filter is closed.
>
> * Allow several encoding filters to specify values other than the default
> that are permitted in decoding filters, such as UnitLength and LowBitFirst
> for LZWEncode.
>
> * Add a parameter for FlateDecode and FlateEncode to control whether or not
> it should use a raw DEFLATE stream.
>
> * New filters: Base64Decode and Base64Encode. You may specify the alphabet
> to use, where line breaking should occur, and whether or not to add padding
> with equal signs.
>
> * Allow defining new filters by adding resources.
>
> * Some output file formats other than PDF might be able to use pdfmark too.
>
> * The "run" operator should accept files as well as file names, like
> Ghostscript does; but, unlike Ghostscript, it should only interpret the
> file as PostScript code. (Another operator could be made to load in a
> separate execution context, and possibly to allow to specify other
> document formats too.)
>
> * Allow the alternative colour space of a Separation or DeviceN colour
> space to be another special colour space (although only a single nesting
> level is allowed in this way); therefore you can tell it to ignore an
> unavailable separation entirely (by specifying [/Separation /None] as the
> alternative colour space), or to simulate it with patterns.
>
> * Add a "cvri" operator to read numbers according to a specified base,
> without needing to prepend something like "16#".
>
> * Add the arctangent function. Also, make trigonometry functions with
> radians as well as with degrees.
>
> * Built-in operators for dealing with strings and files as arrays of
> fixed-length integers (similar than typed arrays in JavaScript). (This
> is useful for dealing with other file formats.)
>
> * DSC is not used.
>
> * Only the Courier font is mandatory; the others are optional. This font
> will need to have the same metrics as the official Courier font, even if
> it is actually a different font (as is the case in Ghostscript).
>
> * Permissions to control parameters are no longer controlled by passwords.
> Any input argument that needs a password is now ignored (and its type is
> also ignored), and password entries in dictionaries are also ignored.
> (There may be other restrictions on controlling them, e.g. the security
> features of the host system, but those are not controlled by PostScript.)
>
> * The currentdevparams and setdevparams operators can be used on files
> that are already open as well as on devices named by strings. (For example,
> it might be used to control terminal settings, locking, etc.)
>
> * An implementation may allow additional editing controls with %lineedit%
> and %statementedit%.
>
> * Add an operator to wait for multiple objects. This can be used in case
> of connecting to multiple sockets or pipes at once, and with extensions
> may be usable for other purposes too.
>
> * A "cvop" operator to convert other objects (such as procedures) into
> an operator that, when executed, will execute the other object.
>
> * Idiom recognition is always disabled by default.
>
> * A variant quit operator that allows specifying the exit code.
>
> * Make a better way to access ligature/kerning data of fonts from within
> PostScript programs.
>
> * You can use a UUID as a XUID by the first entry being 36#UUID and the
> other four are each 32-bits of the UUID number.
>
> * Add a font type which is metrics only and contains an identification of
> the font for the output device. This is used for fonts that are built in
> to the output device or that are not known at compile time. You cannot
> use them with the image device, nor with PostScript operators such as
> charpath. Only some devices will support this use. (For example, with a
> X window output device, it can be used to represent X core fonts. It may
> also be used with some printers that have built-in fonts.)
>
> * Pen shapes, like in METAFONT.
>
> * Allow circular and elliptical arcs to be stored directly in paths. This
> is useful for some output formats, such as SVG.
>
> Please tell me what are your opinions, and if you have other ideas too.
> (I have many other ideas too, than only what I mentioned above. Maybe I
> will write more, later, too.)
>

Unicode today should be almost mandatory.

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Ideas of a new version of PostScript (called "Computer PostScript") news@zzo38computer.org.invalid - 2024-03-06 20:59 -0800
  Re: Ideas of a new version of PostScript (called "Computer PostScript") Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-07 05:29 +0000
    Re: Ideas of a new version of PostScript (called "Computer PostScript") news@zzo38computer.org.invalid - 2024-03-07 15:05 -0800
      Re: Ideas of a new version of PostScript (called "Computer PostScript") Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-07 23:38 +0000
        Re: Ideas of a new version of PostScript (called "Computer PostScript") news@zzo38computer.org.invalid - 2024-03-08 12:00 -0800
          Re: Ideas of a new version of PostScript (called "Computer PostScript") Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-08 20:53 +0000
    Re: Ideas of a new version of PostScript (called "Computer PostScript") David Newall <ghostscript@davidnewall.com> - 2024-03-26 16:20 +1100
      Re: Ideas of a new version of PostScript (called "Computer PostScript") news@zzo38computer.org.invalid - 2024-03-25 23:10 -0700
      Re: Ideas of a new version of PostScript (called "Computer PostScript") Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-26 06:20 +0000
        Re: Ideas of a new version of PostScript (called "Computer PostScript") rlhamil@smart.net (Richard L. Hamilton) - 2024-05-25 16:07 +0000
          Re: Ideas of a new version of PostScript (called "Computer PostScript") Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-05-25 22:31 +0000
  Re: Ideas of a new version of PostScript Lawrence D'Oliveiro <ldo@nz.invalid> - 2024-03-21 07:31 +0000
  Re: Ideas of a new version of PostScript (called "Computer PostScript") Bozo User <anthk@disroot.org> - 2024-03-24 20:45 +0000
    Re: Ideas of a new version of PostScript (called "Computer PostScript") David Newall <ghostscript@davidnewall.com> - 2024-03-26 16:19 +1100

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