Re: [Bug-wget] Problems with (not) building wget against libiconv
On 04/18/2017 02:32 PM, Tim Rühsen wrote: I have some problems with bootstrapping. On Solaris it's: ./bootstrap ./bootstrap: syntax error at line 91: `me_=$' unexpected I experience this as well and use 'bash ./bootstrap'. Autoconf manual says $(...) style command substitution is less portable than using backticks `...`. https://www.gnu.org/software/autoconf/manual/autoconf.html#Shell-Substitutions Hope it helps. I am unable to do any testing at the moment, so sorry. Regards, Akash Rawal
Re: [Bug-wget] [GSoC] Proposal: “Design and implementation of a framework for plugins.”
On 04/02/2017 10:41 PM, Darshit Shah wrote:
* Akash Rawal <argm...@gmail.com> [170331 23:34]:
Hello,
First of all, thanks for the initial review of my proposal!
I have made some changes in response to the comments as well as last
mail on the mailing list by Darshit Shah. Kindly consider reviewing it.
For reference here is the link.
https://docs.google.com/document/d/1SBM-jNG5dJL85C7iK9aid2eDlByrxOsYUNDrk4049vQ/edit?usp=sharing
The proposal is still not final, in the sense that I am analysing the
code for further ideas of what can be customized using plugins.
I was asked to elaborate on rewriting of command line option processing
code. So here are my thoughts on it.
The current code in src/options.c has following drawbacks:
- Built around order-insensitive and idempotent model (Supplying
an option modifies a variable). This might be adequete for wget,
but might not be the case for plugins. Repeated options or
order of options can matter for plugins.
Breaking the order-insensitive and idempotent model of command line
processing is an absolute no-go. It will definitely break many scripts
out there. We do wish to make it easy to transition from Wget to Wget2
and this is a huge change in how options are processed. Also, I see no
clear advantages to why this should be required.
Backward compatibility will only be broken if options are changed,
which I didn't plan to do. wget2 will support all options it
supports now. Existing options shall remain order-insensitive
and idempotent, only new options and plugin-side options may
take advantage of greater flexibility.
Many programs have order-sensitive (e.g. ffmpeg, options
apply to input or output file based on placement) and non-idempotent
(e.g. -v (verbose) option in many program, -vv for higher verbosity)
- The need for keeping the list of options sorted. I don't think
we can expect plugin writers to do the same.
No. Plugins should not be allowed to tinker with certain core
functionalities and that includes how options are processed.
- And most importantly, options cannot be added at runtime.
Which is a very good thing. Keeping everything at compile time means we
can have most of that code on the stack without the need for costly
dynamic memory allocations on each invokation. Options processing code
should definitely not be dynamic.
Okay if that is your requirement I'll remove it from my proposal.
So far I think rewriting the option processing code would be easier
than trying to patch existing code to support custom options.
Some parts of the original code could be reused but structure
would undergo a drastic change anyway.
Easier? Have you every tried writing one? The number of use cases and
corner cases you'd have to handle is massive. That alone could be an
entire GSoC project. You can't expect to write it as a byproduct of your
project.
I have written simpler ones. But even in wget's code option processor is
not so large (~400 LOC, starting from src/option.c:853)
Cases for long options:
--option
--option=value
--option value
--no-option
Cases for short options:
-x
-x value
-xvalue
-xyzw
-xyzvalue
-xyz value
The idea I have is to expose an interface for plugins to describe
command line options they want to receive. I have attached a
prototype header. From this interface, wget will have a list of
command line options to support, along with plugin function to
be called for handling plugin specific options. In addition to
using this to parse command line, wget can Use the descriptions
and category information provided to generate --help output.
First let me ask you, how exactly do you envision a user using plugins
with Wget2? How are plugins selected? How does the user even know if a
plugin exists?
How about:
$ wget_plugins="foo" wget2 --foo-option http://example.com/file.html
Or:
$ wget2 --plugin=foo --foo-option http://example.com/file.html
Hypothetical example: music site parser that filters by rating
$ wget2 --plugin=music_rating_filter --music_min_rating=4 \
--recursive --level=20 \
http://example_music_site.com/music/1
Multiple plugins:
$ wget_plugins="foo:bar" wget2 --plugin=foo --plugin=bar \
--foo-option --bar-option=value http://example.com/file.html
Or:
$ wget2 --plugin=foo --plugin=bar --foo-option --bar-option=value \
http://example.com/file.html
$ #The above is also an example of non-idempotent option --plugin
Loading plugins which are not installed:
$ wget2 --local-plugin=/path/to/libfoo.so --foo-option \
http://example.com/file.html
And regarding user knowing which plugins are installed:
$ wget2 --list-plugins
foo
bar
music_rating_filter
Plugins could be installed in a directory like
${PREFIX}/lib/wget/plugins/. Many software do like this.
Regarding the need to support plugin side addition of command line
options at the first p
[Bug-wget] [GSoC] Proposal: “Design and implementation of a framework for plugins.”
Hello,
First of all, thanks for the initial review of my proposal!
I have made some changes in response to the comments as well as last
mail on the mailing list by Darshit Shah. Kindly consider reviewing it.
For reference here is the link.
https://docs.google.com/document/d/1SBM-jNG5dJL85C7iK9aid2eDlByrxOsYUNDrk4049vQ/edit?usp=sharing
The proposal is still not final, in the sense that I am analysing the
code for further ideas of what can be customized using plugins.
I was asked to elaborate on rewriting of command line option processing
code. So here are my thoughts on it.
The current code in src/options.c has following drawbacks:
- Built around order-insensitive and idempotent model (Supplying
an option modifies a variable). This might be adequete for wget,
but might not be the case for plugins. Repeated options or
order of options can matter for plugins.
- The need for keeping the list of options sorted. I don't think
we can expect plugin writers to do the same.
- And most importantly, options cannot be added at runtime.
So far I think rewriting the option processing code would be easier
than trying to patch existing code to support custom options.
Some parts of the original code could be reused but structure
would undergo a drastic change anyway.
The idea I have is to expose an interface for plugins to describe
command line options they want to receive. I have attached a
prototype header. From this interface, wget will have a list of
command line options to support, along with plugin function to
be called for handling plugin specific options. In addition to
using this to parse command line, wget can Use the descriptions
and category information provided to generate --help output.
Regarding the need to support plugin side addition of command line
options at the first place, here are my thoughts.
Plugins might need additional data from the user. I can think
of 3 ways in which it can be done:
1. Environment variables.
2. Files with well-known names.
3. Command line.
Environment variables have a disadvantage that they are automatically
passed to the subprocesses, creating a chance for interference.
Also, name clashes cannot be discovered.
Using files with well-known names has a chance of interference
with parallel running instances of wget.
None of these disadvantages are shared with using command line
options.
Opinions are welcome.
Regards,
Akash Rawal.
/* This is a prototype. Final product can be different. */
/**
* \addtogroup argp
* \{
*
* This section documents functions for extending command line
* option processing.
*
* The procedure is to first create a new option list using
* _wget_argp_optlist_init_. Options and categories are then added by
* _wget_argp_optlist_add_option_ and _wget_argp_optlist_add_category_.
* Finally, options are added for consideration by _wget_argp_add_optlist_.
* After this, option list should be free'd using _wget_argp_optlist_free_.
*/
///Data structure for command line options
typedef struct _wget_argp_optlist_t wget_argp_optlist_t;
/**Creates a new option list
* \return A newly constructed option list. Free with _wget_argp_optlist_free_
*/
wget_argp_optlist_t *wget_argp_optlist_init();
/**Frees all memory associated with _optlist_.
* \param optlist An option list created with _wget_argp_optlist_init_
*/
void wget_argp_optlist_free(wget_argp_optlist_t *optlist);
/**Adds a new category to command line options.
* \param optlist An option list
* \param catid Category identifier. This must be unique.
* \param desc Description which will appear in the _--help_ output.
*/
void wget_argp_optlist_add_category
(wget_argp_optlist_t *optlist, const char *catid, const char *desc);
///Type of command line options supported
typedef enum
{
///Option accepts no arguments
WGET_ARGP_ARG_NONE,
//Option requires argument.
WGET_ARGP_ARG_REQUIRED,
//Option accepts argument, but it is optional.
WGET_ARGP_ARG_OPTIONAL
} wget_argp_option_arg_type;
/**Adds a command line option to option list.
* \param catid Category identifier to specify which category to
* add option to in _--help_ output.
* \param optlist An option list
* \param id A numeric ID to associate with the option.
* \param short_option Single letter short option, or 0 for no short option.
* \param option Long option.
* \param arg_desc A short description of the argument it takes.
* \param argtype Argument accepting policy. See _wget_argp_option_arg_type_
* \param negatable Nonzero if _option_ can be supplied as --no-option.
* \param desc Description which will appear in _--help_ output.
*/
void wget_argp_optlist_add_option
(wget_argp_optlist_t *optlist,
const char *catid, int id,
char short_option, const char *option, const char *arg_desc,
wget_argp_option_arg_type argtype, int negatable,
const char *desc);
/**Type of function to be registered as a callback
* \param id Identifier of the option matched
