[Bioc-devel] Use Imports instead of Depends in the DESCRIPTION files of bioconductor packages

[Hervé Pagès]

Hi Gordon,

My guess is that it has to do with how many symbols get exported.
For example on my machine, doing library(limma) in a fresh session
takes 0.261s and triggers export of 292 symbols (as reported by
ls(..., all.names=TRUE)). Doing library(GenomicRanges) in a fresh
session takes 2.724s and triggers export of 1581 symbols (counting
the symbols exported by all the packages that get loaded).

Michael it's great to hear that somebody is working on speeding up
the code in charge of this.

Happy New Year everybody!
H.


On 12/31/2014 06:07 PM, Gordon K Smyth wrote:
> Hi Michael,
>
> What aspect of the methods package causes the slowness?
>
> There are many packages (limma for one) that depend on methods but load
> quickly.
>
> Regards
> Gordon
>
>
>> Date: Wed, 31 Dec 2014 09:17:01 -0800
>> From: Michael Lawrence <lawrence.michael at gene.com>
>> To: Peng Yu <pengyu.ut at gmail.com>
>> Cc: Bioconductor Package Maintainer <maintainer at bioconductor.org>,
>>     "bioc-devel at r-project.org" <bioc-devel at r-project.org>
>> Subject: Re: [Bioc-devel] [devteam-bioc] Use Imports instead of
>>     Depends in the DESCRIPTION files of bioconductor packages.
>>
>> The slowness is due to the methods package. We're working on it.
>>
>> Michael
>>
>> On Wed, Dec 31, 2014 at 8:47 AM, Peng Yu <pengyu.ut at gmail.com> wrote:
>>
>>> On Wed, Dec 31, 2014 at 9:41 AM, Martin Morgan <mtmorgan at fredhutch.org>
>>> wrote:
>>>> On 12/24/2014 07:31 PM, Maintainer wrote:
>>>>>
>>>>> Hi,
>>>>>
>>>>> Many bioconductor packages Depends on other packages but not Imports
>>>>> other packages. (e.g., IRanges Depends on BiocGenerics.) Imports is
>>>>> usually preferred to Depends.
>>>>>
>>>>>
>>>>>
>>> http://stackoverflow.com/questions/8637993/better-explanation-of-when-to-use-imports-depends
>>>
>>>>> http://obeautifulcode.com/R/How-R-Searches-And-Finds-Stuff/
>>>>>
>>>>> Could the unnecessary Depends be forced to be replaced by Imports?
>>>>> This should improve the package load time significantly.
>>>>
>>>>
>>>> R package symbols and other objects are collated at build time into a
>>> 'name
>>>> space'. When used,
>>>>
>>>> - Import: loads the name space from disk.
>>>> - Depends: loads the name space from disk, and attaches it to the
>>> search()
>>>> path.
>>>>
>>>> Attaching is very inexpensive compared to loading, so there is no speed
>>>> improvement gained by Import'ing instead of Depend'ing.
>>>
>>> Yes. For example, changing Depends to Imports does not improve the
>>> package load time much.
>>>
>>> But loading a package in 4 sec seems to be too long.
>>>
>>>>  system.time(suppressPackageStartupMessages(library(MBASED)))
>>>    user  system elapsed
>>>   4.404   0.100   4.553
>>>
>>> For example, it only takes 10% of the time to load ggplot2. It seems
>>> that many bioconductor packages have similar problems.
>>>
>>>> system.time(suppressPackageStartupMessages(library(ggplot2)))
>>>    user  system elapsed
>>>   0.394   0.036   0.460
>>>
>>>> The main reason to Depend: on a package is because the symbols
>>>> defined by
>>>> the package are needed by the end-user. Import'ing a package is
>>> appropriate
>>>> when the package provides functionality only relevant to the package
>>> author.
>>>
>>> What causes the load time to be too long? Is it because exporting too
>>> many functions from all dependent packages to the global namespace?
>>>
>>>> There are likely to be specific packages that mis-use Depends; packages
>>> such
>>>> as IRanges, GenomicRanges, etc use Depends: as intended, to  provide
>>>> functions that are useful to the end user.
>>>>
>>>> Maintainers are certainly encouraged to think carefully about adding
>>>> packages providing functionality irrelevant to the end-user to the
>>> Depends:
>>>> field. The codetoolsBioC package (available from svn, see
>>>> http://bioconductor.org/developers/how-to/source-control/) provides
>>>> some
>>>> mostly reliable hints to package authors about correctly formulating a
>>>> NAMESPACE file to facilitate using Imports: instead of Depends:.
>>>>
>>>> General questions about Bioconductor packages should be addressed to
>>>> the
>>>> support forum https://support.bioconductor.org.
>>>>
>>>> Questions about Bioconductor development (such as this) should be
>>> addressed
>>>> to the bioc-devel mailing list (subscription required)
>>>> https://stat.ethz.ch/mailman/listinfo/bioc-devel.
>>>>
>>>> I have cc'd the bioc-devel mailing list; I hope that is ok.
>>>
>>>
>>>
>>> --
>>> Regards,
>>> Peng
>
> ______________________________________________________________________
> The information in this email is confidential and inte...{{dropped:20}}