What advantages and/or disadvantages are there to using a "snippets" plugin, e.g. snipmate, ultisnips, for VIM as opposed to simply using the builtin "abbreviations" functionality?
Are there specific use-cases where declaring iabbr, cabbr, etc. lack some major features that the snippets plugins provide? I've been unsuccessful in finding a thorough comparison between these two "features" and their respective implementations.
As #peter-rincker pointed out in a comment:
It should be noted that abbreviations can execute code as well. Often via <c-r>= or via an expression abbreviation (<expr>). Example which expands ## to the current file's path: :iabbrev ## <c-r>=expand('%:p')<cr>
As an example for python, let's compare a snipmate snippet and an abbrev in Vim for inserting lines for class declaration.
Snipmate
# New Class
snippet cl
class ${1:ClassName}(${2:object}):
"""${3:docstring for $1}"""
def __init__(self, ${4:arg}):
${5:super($1, self).__init__()}
self.$4 = $4
${6}
Vimscript
au FileType python :iabbr cl class ClassName(object):<CR><Tab>"""docstring for ClassName"""<CR>def __init__(self, arg):<CR><Tab>super(ClassName, self).__init__()<CR>self.arg = arg
Am I missing some fundamental functionality of "snippets" or am I correct in assuming they are overkill for the most part, when Vim's abbr and :help template templates are able to do all most of the stuff snippets do?
I assume it's easier to implement snippets, and they provide additional aesthetic/visual features. For instance, if I use abbr in Vim and other plugins for running/testing python code inside vim--e.g. syntastic, pytest, ropevim, pep8, etc--am I missing out on some key features that snippets provide?
Everything that can be done with snippets can be done with abbreviations and vice-versa. You can have (mirrored or not) placeholders with abbreviations, you can have context-sensitive snippets.
There are two important differences:
Abbreviations are triggered when the abbreviation text has been typed, and a non word character (or esc) is hit. Snippets are triggered on demand, and shortcuts are possible (no need to type while + tab. w + tab may be enough).
It's much more easier to define new snippets (or to maintain old ones) than to define abbreviations. With abbreviations, a lot of boiler plate code is required when we want to do neat things.
There are a few other differences. For instance, abbreviations are always triggered everywhere. And seeing for expanded into for(placeholder) {\n} within a comment or a string context is certainly not what the end-user expects. With snippets, this is not a problem any more: we can expect the end-user to know what's he's doing when he asks to expand a snippet. Still, we can propose context-aware snippets that expand throw into #throw {domain::exception} {explanation} within a comment, or into throw domain::exception({message}); elsewhere.
Snippets
Rough superset of Vim's native abbreviations. Here are the highlights:
Only trigger on key press
Uses placeholders which a user can jump between
Exist only for insert mode
Dynamic expansions
Abbreviations
Great for common typos and small snippets.
Native to Vim so no need for plugins
Typically expand on whitespace or <c-]>
Some special rules on trigger text (See :h abbreviations)
Can be used in command mode via :cabbrev (often used to create command aliases)
No placeholders
Dynamic expansions
Conclusion
For the most part snippets are more powerful and provide many features that other editors enjoy, but you can use both and many people do. Abbreviations enjoy the benefit of being native which can be useful for remote environments. Abbreviations also enjoy another clear advantage which is can be used in command mode.
Snippets are more powerful.
Depending on the implementation, snippets can let you change (or accept defaults for) multiple placeholders and can even execute code when the snippet is expanded.
For example with ultisnips, you can have it execute shell commands, vimscript but also Python code.
An (ultisnips) example:
snippet hdr "General file header" b
# file: `!v expand('%:t')`
# vim:fileencoding=utf-8:ft=`!v &filetype`
# ${1}
#
# Author: ${2:J. Doe} ${3:<jdoe#gmail.com>}
# Created: `!v strftime("%F %T %z")`
# Last modified: `!v strftime("%F %T %z")`
endsnippet
This presents you with three placeholders to fill in (it gives default values for two of them), and sets the filename, filetype and current date and time.
After the word "snippet", the start line contains three items;
the trigger string,
a description and
options for the snippet.
Personally I mostly use the b option where the snippet is expanded at the beginning of a line and the w option that expands the snippet if the trigger string starts at the beginning of a word.
Note that you have to type the trigger string and then input a key or key combination that actually triggers the expansion. So a snippet is not expanded unless you want it to.
Additionally, snippets can be specialized by filetype. Suppose you want to define four levels of headings, h1 .. h4. You can have the same name expand differently between e.g. an HTML, markdown, LaTeX or restructuredtext file.
snippets are like the built-in :abbreviate on steroids, usually with:
parameter insertions: You can insert (type or select) text fragments in various places inside the snippet. An abbreviation just expands once.
mirroring: Parameters may be repeated (maybe even in transformed fashion) elsewhere in the snippet, usually updated as you type.
multiple stops inside: You can jump from one point to another within the snippet, sometimes even recursively expand snippets within one.
There are three things to evaluate in a snippet plugin: First, the features of the snippet engine itself, second, the quality and breadth of snippets provided by the author or others; third, how easy it is to add new snippets.
Related
I just set up my VS Code to use Black, the python formatter. The default format puts a dict key on a new line when referencing a value, like this,
my_function_call(
my_dict[
"my_key"
],
function_param2=var,
function_param3=another_var
)
I never write keys on a new line like that when referencing a dictionary. Instead, I would rather set it up on the same line, like so,
my_function_call(
function_param1=my_dict["my_key"],
function_param2=var,
function_param3=another_var
)
Is there a way to save specific modifications like this, or is black a take-what-you-get kind of extension? I haven't found anything in their docs or in a google search mentioning modifications
EDIT: Just checked and this is not due to black's default line length. The line of code I'm testing is not longer than default 88 chars.
No, you cannot configure how Black formats your code except for setting the line length. It intentionally doesn't have options to control formatting.
Black is the uncompromising Python code formatter. By using it, you agree to cede control over minutiae of hand-formatting. – PyPI
I would like to add an additional syntax to Python-Markdown: if n is a positive integer, >>n should expand into n. (Double angled brackets (>>) is a conventional syntax for creating links in imageboard forums.)
By default, Python-Markdown expands >>n into nested blockquotes: <blockquote><blockquote>n</blockquote></blockquote>. Is there a way create links out of >>n, while preserving the rest of blockquote's default behavior? In other words, if x is a positive integer, >>x should expand into a link, but if x is not a positive integer, >>x should still expand into nested blockquotes.
I have read the relevant wiki article: Tutorial 1 Writing Extensions for Python Markdown. Based on what I learned in the wiki, I wrote a custom extension:
import markdown
import xml.etree.ElementTree as ET
from markdown.extensions import Extension
from markdown.inlinepatterns import Pattern
class ImageboardLinkPattern(Pattern):
def handleMatch(self, match):
number = match.group('number')
# Create link.
element = ET.Element('a', attrib={'href': f'#post-{number}'})
element.text = f'>>{number}'
return element
class ImageboardLinkExtension(Extension):
def extendMarkdown(self, md):
IMAGEBOARD_LINK_RE = '>>(?P<number>[1-9][0-9]*)'
imageboard_link = ImageboardLinkPattern(IMAGEBOARD_LINK_RE)
md.inlinePatterns['imageboard_link'] = imageboard_link
html = markdown.markdown('>>123',
extensions=[ImageboardLinkExtension()])
print(html)
However, >>123 still produces <blockquote><blockquote>123</blockquote></blockquote>. What is wrong with the implementation above?
The problem is that your new syntax conflicts with the preexisting blockquote syntax. Your extension would presumably work if it was ever called. However, due to the conflict, that never happens. Note that their are five types of processors. As documented:
Preprocessors alter the source before it is passed to the parser.
Block Processors work with blocks of text separated by blank lines.
Tree Processors modify the constructed ElementTree
Inline Processors are common tree processors for inline elements, such as *strong*.
Postprocessors munge of the output of the parser just before it is returned.
Of importance here is that the processors are run in that order. In other words, all block processors are run before any inline processors are run. Therefore, the blockquote block processor runs first on your input and removes the double angle bracket, wrapping the rest of the line in double blockquote tags. By the time your inline processor sees the document, your regex will no longer match and will therefore never be called.
That being said, an inline processor is the correct way to implement a link syntax. However, you would need to do one of two things to make it work.
Alter the syntax so that it does not clash with any preexisting syntax; or
Alter the blockquote behavior to avoid the conflict.
Personally, I would recommend option 1, but I understand you are trying to implement a preexisting syntax from another environment. So, if you want to explore option 2, then I would suggest perhaps making the blockquote syntax a little more strict. For example, while it is not required, the recommended syntax is to always insert a space after the angle bracket in a blockquote. It should be relatively simple to alter the BlockquoteProcessor to require the space, which would cause your syntax to no longer clash.
This is actually pretty simple. As you may note, the entire syntax is defined via a rather simple regex:
RE = re.compile(r'(^|\n)[ ]{0,3}>[ ]?(.*)')
You simply need to rewrite that so that 0 whitespace is no longer accepted (> rather than >[ ]?). First import and subclass the existing processor and then override the regex:
from markdown.blockprocessors import BlockquoteProcessor
class CustomBlockquoteProcessor(BlockquoteProcessor):
RE = re.compile(r'(^|\n)[ ]{0,3}> (.*)')
Finally, you just need to tell Markdown to use your custom class rather than the default. Add the following to the extendMarkdown method of your ImageboardLinkExtension class:
md.parser.blockprocessors.register(CustomBlockQuoteProcessor(md.parser), 'quote', 20)
Now the blockquote syntax will no longer clash with your link syntax and you will get an opportunity to have your code run on the text. Just be careful to remember to always include the now required space for any actual blockquotes.
I really hate having spread out code, I am looking at a bunch of long code with parameters and arguments that are taking up way to much space.
def __init__(self,
network,
value_coef,
entropy_coef,
lr=None,
eps=None,
max_grad_norm=None,
conv=False):
Seems the guy who wrote it forced a 50 character line limit, I whole heartedly disagree. I would much rather it looked like this.
def __init__(self, network, value_coef, entropy_coef, lr=None, eps=None, max_grad_norm=None, conv=False):
There is also more nonsense like this which I would like to get rid of.
if self.conv:
grid_obs = rollouts.grid_obs[:-1]\
.view(-1, *rollouts.grid_obs.size()[2:])
dest_obs = rollouts.dest_obs[:-1]\
.view(-1, *rollouts.dest_obs.size()[2:])
obs = (grid_obs, dest_obs)
I am using VS code for the python and am an ex Intellij user and am missing all the built in code formatting code tools. Any one got any tips? I have been looking at autopep8 but it seems they are missing that functionality.
First, that's not 50 chars limit but 79 (as per pep8 conventions) and the way you would like to have it wouldn't be pep8 compliant as it's over 100 columns.
So, for the first snippet you can have it the way you don't like it (which is the correct way) or let your formatter know that you want the line-length to be over 79 columns.
For the second snippet you can remove the escape character \ and let the formatter do its job. I don't think it's 'nonsense' as you call it, but feel free to format it differently.
Autopep8 or Black both work very well and they are not missing any functionality.
Provided you installed one or the other, you have to add the proper key/value pair to your settings.json:
"python.formatting.provider": "autopep8" // (or "black")
If you use autopep8, for example, you can specify the line length you want (150 in your case) by adding this to your settings.json file:
"python.formatting.autopep8Args": [
"--line-length=150"
]
The same goes for black. In that case the value would be:
"python.formatting.blackArgs": [
"--line-length=150"
]
Formatting with that parameter will wrap your code to that amount.
You can format code with alt+shift+f (on a Mac) or right click on the editor and "Format Document".
I am trying to get Vim to syntax highlight any file that ends with extension .Rtex in the following way:
All top level text is highlighted as TeX
Exception: any text enclosed in \begin{python}...\end{python} is highlighted as Python
I am able to achieve each of these criteria individually, but unable to achieve both simultaneously. I think that somehow the TeX highlighting overrides my Python-highlighted regions, or prevents them from taking effect, and I am stuck trying to figure out how.
First step: edit .vimrc to give files with extension .Rtex the filetype rtex:
au BufRead *.Rtex setf rtex
Second step: create ~/.vim/syntax/rtex.vim. It is the contents of this file that will determine how to highlight .Rtex files.
Third step: enable general top-level TeX highlighting, by making rtex.vim look like this:
runtime! syntax/tex.vim
If I now open a .Rtex file, the entire file is highlighted as TeX, including any text within \begin{python}...\end{python}, as expected.
Fourth step: follow the instructions in Vim's :help syn-include to include python highlighting and apply it to all regions delimited by \begin{python} and \end{python}. My rtex.vim file now looks like this:
runtime! syntax/tex.vim
unlet! b:current_syntax
syntax include #Python syntax/python.vim
syntax region pythonCode start="\\begin{python}" end="\\end{python}" contains=#Python
The unlet! b:current_syntax command is meant to force the python.vim syntax file to execute even though an existing syntax (TeX) is already active.
Problem: If I now open a .Rtex file, the entire file is still highlighted only as TeX. The \begin{python}...\end{python} region seems to have no effect.
Experiment: If I remove or comment out the runtime! command, I do get python highlighting, within the \begin{python}...\end{python} regions, exactly as desired, but of course no TeX highlighting in the remainder of the document. I therefore conclude that the TeX highlighting is somehow responsible for preventing the python regions from taking effect.
Can a Master of Vim offer me any suggestions? I am currently stumped. I have looked at several pages and stackoverflow questions that seem relevant, but none of them have so far led to a solution:
http://vim.wikia.com/wiki/Different_syntax_highlighting_within_regions_of_a_file
Embedded syntax highligting in Vim
VIM syntax highlighting of html nested in yaml
After some more study of the manual, and much more trial and error, I have finally answered my own question (a simultaneously embarrassing and sublime accomplishment), which I now preserve here for posterity.
Basically, I think the problem is that the python highlighting wouldn't take effect because the pythonCode region was itself contained in a region or highlight group defined by tex.vim, so it wasn't top-level. The solution is to also include (rather than just runtime) tex.vim, giving it a name like #TeX, and then add containedin=#TeX to my python region definition. So syntax/rtex.vim now looks like this:
let b:current_syntax = ''
unlet b:current_syntax
runtime! syntax/tex.vim
let b:current_syntax = ''
unlet b:current_syntax
syntax include #TeX syntax/tex.vim
let b:current_syntax = ''
unlet b:current_syntax
syntax include #Python syntax/python.vim
syntax region pythonCode matchgroup=Snip start="\\begin{python}" end="\\end{python}" containedin=#TeX contains=#Python
hi link Snip SpecialComment
let b:current_syntax = 'rtex'
And this works! I'm not sure if all of those unlet b:current_syntax commands are strictly necessary. I also gave the python region delimiters a matchgroup (Snip) so that they can be highlighted themselves (with the SpecialComment color), rather than left just plain, which is apparently what happens by default, since they are no longer considered part of the TeX.
Now it is a trivial thing to add more highlight regions for different languages (e.g., \begin{Scode}...\end{Scode}), which is great if you're getting into literate programming -- the original motivation for my question.
Edit: here is a screenshot showing how it works with Python and R code embedded in a TeX document:
I don't know if it helps, but a hack I use with my Rnw files that use both tex and rnoweb features is as follows:
au BufEnter *.Rnw set filetype=tex | set filetype=rnoweb
Would an adapted version work in your case?
I'm writing a C parser using PLY, and recently ran into a problem.
This code:
typedef int my_type;
my_type x;
Is correct C code, because my_type is defined as a type previously to
being used as such. I handle it by filling a type symbol table in the
parser that gets used by the lexer to differentiate between types and
simple identifiers.
However, while the type declaration rule ends with SEMI (the ';' token), PLY shifts the token my_type from the second line before deciding it's done with the first one. Because of this, I have no chance to pass the update in the type symbol table to the lexer and it
sees my_type as an identifier and not a type.
Any ideas for a fix ?
The full code is at: http://code.google.com/p/pycparser/source/browse/trunk/src/c_parser.py
Not sure how I can create a smaller example out of this.
Edit:
Problem solved. See my solution below.
Not sure why you're doing that level of analysis in your lexer.
Lexical analysis should probably be used to separate the input stream into lexical tokens (number, line-change, keyword and so on). It's the parsing phase that should be doing that level of analysis, including table lookups for typedefs and such.
That's the way I've always separated the duties between lexx and yacc, my tools of choice.
With some help from Dave Beazley (PLY's creator), my problem was solved.
The idea is to use special sub-rules and do the actions in them. In my case, I split the declaration rule to:
def p_decl_body(self, p):
""" decl_body : declaration_specifiers init_declarator_list_opt
"""
# <<Handle the declaration here>>
def p_declaration(self, p):
""" declaration : decl_body SEMI
"""
p[0] = p[1]
decl_body is always reduced before the token after SEMI is shifted in, so my action gets executed at the correct time.
I think you need to move the check for whether an ID is a TYPEID from c_lexer.py to c_parser.py.
As you said, since the parser is looking ahead 1 token, you can't make that decision in the lexer.
Instead, alter your parser to check ID's to see if they are TYPEID's in declarations, and, if they aren't, generate an error.
As Pax Diablo said in his excellent answer, the lexer/tokenizer's job isn't to make those kinds of decisions about tokens. That's the parser's job.