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OEP:pkg

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{{Warning|This page has not been revisited since 2014. Please refer to the GNU Octave manual for information about {{manual|pkg}}.}}
 
== Abstract ==
This OEP refers to Octave's design of the pkg system. The purpose of this system
See the user cases section below for several examples.
 
The definition of a package manager according to wikipedia:
 
* Verifying file checksums to ensure correct and complete packages;
* Verifying digital signatures to authenticate the origin of packages;
* Applying file archivers to manage encapsulated files;
* Upgrading software with latest versions, typically from a software repository;
* Grouping of packages by function to reduce user confusion;
* Managing dependencies to ensure a package is installed with all packages it requires. This resolved the problem known as Dependency Hell.
== Available vs Loaded ==
associated file just like the db files for the local installs. To load an external
package, the path for the db file needs to be passed to pkg and the db named (because
there may be more than onde one db.
These are most like the less used type of packages and will require a bit more
If the user decides to make a global package install (install the package using pkg while
runnig running Octave with sudo), then he's trying to act as system administrator and should know
what he's doing. If he breaks it, its his own fault. Installation of system-wide software
is meant to be handled by the system packaging tool. It is just not possible to make pkg
Also, supporting multiple packages versions means that the word "all" to refer to all
packages has new limitations. Should we load only the latest version of each package?
And if there's multiple packages with the same version on varios various db, which one should
be loaded? I'd propose the default to be:
- load the latest version availaleavailable
- load the local install of the package
- load the global install of the package
For package names, the proposal is to limit package names to the same as variable
names (makes it even easier to check validaity validity with isvarname). So package name
must start with a letter, and otherwise be comprised of alphanumeric and underscores
characters. Unlike variable names, package names will not be case sensitive since
sensitive (creating directories named Image and image would not be possible in FAT
systems).
 
== Version numbers ==
 
=== specifying version ===
Actions dependent on a package version can be specified with a -version modifier for that
action. It is however necessary to define the default order. Comparison operators
should be used to specify versions. If no comparison is use then greater than or
equal is assumed. So that the following:
 
;pkg load image
: loads latest version of the image package. If package is not installed, give error
;pkg load -version 1.0.5 image
: load the latest version greater than or equal to 1.0.5. If no such version found, give error
;pkg load -version >=1.0.5 image
: same as not specifying comparison
;pkg load -version >1.0.5 image
: load anything above that version (does it make sense supporting this? It's not a lot of trouble...)
;pkg load -version =1.0.5 image
: load image package only if the same version (should we use == instead? Why not only =? Should not support both syntax)
;pkg load -version !1.0.5 image
: load any image package available except 1.0.5 (because regressions do exist)
 
For the other 2 remaining comparisons (< and <=), the question used for > and >=
is the same. Does it make sense to support both? For ''greater than'', the only
thing that makes sense is ''greater than or equal'' and for ''lesser than'', the
only think that makes sense is ''only lesser than'' since people will mark them
as the first release that implemented, or the first release that no longer had,
a specific feature.
 
Whatever code is used on this section should also be used for solving package
dependencies.
 
Should versions take precedence over the database for loading order? For example,
if there is a global installation of image 1.0.5 and a 2.0.0 version on an external
database named labdev, what version should be loaded?
 
;pkg load image
: load version 1.0.5 from global (database takes precedence over version)
;pkg load -version >1.0.0 image
: load version 1.0.5 from global (database takes precedence over version)
;pkg load -version >2.0.0 image
: load version 2.0.0 from labdev (only version that meets the requirements)
;pkg load -version >1.0.0 -db labdev image
: load version 2.0.0 from labdev (while database takes precedence, labdev was specified so we load the latest)
 
Should the -db modifier make pkg ignore completely version? If a system has signal
version 1.0.0 on an external named labdev, and 1.2.0 on a global, what should be loaded?
 
;pkg load signal
: load version 1.2.0 from global
;pkg load -db labdev image
: load latest version from global or from labdev?
 
=== version definition ===
The current implementation only accepts versions on the format x.y.z. This does
not allow for dev versions, beta or release candidates releases such x.y.z-rc0, x.y.z+, etc
 
We have compare_versions in core to check for version numbers, whatever is decided
should be used with compare_version (or compare_version should be made to support it).
== User cases ==
While using Octave 3.6.2, Denise installs the new version of the package
"pkg install -forge financial". The files for the previous version of the package
are kept altough although "pkg load financial" will only load the latest version. However, when
Denise is using Octave 3.4.3, as financial 1.2.0 requires Octave 3.6.0, pkg load
will only load financial 1.0.4.
Lisa is using Octave in a remote machine on the biochemistry department. The
system administrator installed Octave 3.6.2, signal package 1.2.0, and
general 1.0.0. Lisas Lisa uses all of them but she also requires the image package.
However, the system administrator does not have time to access security issues
with the package and tells her to install that package locally. She runs "pkg
does not want to make the update and tells her to build it herself locally
=== User case #5 : users (no sudo) sharing Octave installation with local & global packages ===
Diana is a student that wants to run her code in the departmental cluster. However,
the system does not have an installation of Octave and she needs to install it on
to her own list of available packages. which she can load.
=== User case #6 : Automatic dependency tracking ===
John is a professor of biomechanics and uses Octave on his classes. Most of the
exercises he gives to the class require the use of multiple packages in Octave
metapackage for his student listing all required packages. The students install
it with "pkg install -url path-to-his-metapackage". The metapackage has no file
it simply lists a bunch of package has as dependencies. Since pkg solves this
dependencies automatically, a message showing which packages will be installed
is displayed before doing it.
=== User case #7: Package testing ==="pkg test" command that would run all tests for a given package. == Where to install things ===
These should not be hardcoded and taken from octave_config_info. There's many paths there whose purpose is explained on octave sources [http://hg.savannah.gnu.org/hgweb/octave/file/default/build-aux/common.mk buil-aux/common.mk] (see the ''Where To Install Things'' and ''Octave-specific directories'' sections on that file.)
 
[[Category:Packages]]

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