dochelp {mvbutils}

Documentation (informal help)

Description

dochelp(topic) will be invoked by the replacement help if conventional help fails to find documentation for topic topic. If topic is an object with a doc attribute (or failing that if <<topic>> or <<topic>>.doc is a character vector), then the attribute (or the character object) will be formatted and displayed by the pager or browser. dochelp is not usually called directly.

Usage

# Not usually called directly
# If it is, then normal usage is: dochelp( topic)
dochelp( topic, doc, help_type=c( "text", "html"))
# Set options( mvb_help_type="text") if the browser gives you grief

Arguments

topic

(character) name of the object to look for help on, or name of "...doc" character object– e.g. either thing or thing.doc if the character object is thing.doc.

doc

(character or list)– normally not set, but deduced by default from topic; see Details.

help_type

as per help. Defaults to getOption( "mvb_help_type") in normal usage, which in turn defaults to getOption( "help_type") as for standard help. Only "text" and "html" are supported by dochelp; anything else maps to "text", which invokes R's internal pager.

Details

dochelp will only be called if the original help call was a simple help( topic=X, ...) form, with X not a call and with no try.all.packages or type or lib.loc arguments (the other help options are OK).

The doc argument defaults to the doc attribute of get("topic"). The only reason to supply a non-default argument would be to use dochelp as a pager; this might have some value, since dochelp does reformat character vectors to fit nicely in the system pager window, one paragraph per element, using strwrap. Elements starting with a "%" symbol are not displayed.

To work with dochelp, a doc attribute should be either:

• a character vector, of length >=1. New elements get line breaks in the pager. Or:

• a length-one list, containing the name of another object with a doc attribute. dochelp will then use the doc attribute of that object instead. This referencing can be iterated.

If the documentation is very informal, start it with a blank line to prevent find.documented( ..., doctype="Rd") from finding it.

With help_type="text", the doco will be re-formatted to fit the pager; each paragraph should be a single element in the character vector. Elements starting with a % will be dropped (but may still be useful for doc2Rd).

With help_type="html", the doco will be passed thru doc2Rd and then turned into HTML. doc2Rd is pretty forgiving and has a fair crack at converting even very informal documentation, but does have its limits. If there is an error in the doc2Rd conversion then help_type will be reset to "text".

flatdoc offers an easy way to incorporate plain-text (flat-format) documentation– formal or informal– in the same text file as a function definition, allowing easy maintenance. The closer you get to the displayed appearance of formal R-style help, the nicer the results will look in a browser (assuming help_type="html"), but the main thing is to just write some documentation– the perfect is the enemy of the good in this case!

Author(s)

Mark Bravington

See Also

flatdoc, doc2Rd, find.documented, strwrap

Examples

#
myfun <- structure( function() 1,
  doc="Here is some informal documentation for myfun\n")
dochelp( "myfun")
help( "myfun") # calls dochelp