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"""Different""", "quote", 'types' in function?

I am trying to figure out if the different quote types make a difference functionally. I have seen people say its preference for "" or '' but what about """ """? I tested it in a simple code to see if it would work and it does. I was wondering if """ triple quotes """ have a functional purpose for defined function arguments or is it just another quote option that can be used interchangeably like "" and ''?
As I have seen many people post about "" and '' I have not seen a post about """ """ or ''' ''' being used in functions.
My question is: Does the triple quote have a unique use as an argument or is it simply interchangeable with "" and ''? The reason I think it might have a unique function is because it is a multi line quote and I was wondering if it would allow a multi line argument to be submitted. I am not sure if something like that would even be useful but it could be.
Here is an example that prints out what you would expect using all the quote types I know of.
def myFun(var1="""different""",var2="quote",var3='types'):
return var1, var2, var3
print (myFun('All','''for''','one!'))
Result:
('All', 'for', 'one!')
EDIT:
After some more testing of the triple quote I did find some variation in how it works using return vs printing in the function.
def myFun(var1="""different""",var2="""quote""",var3='types'):
return (var1, var2, var3)
print(myFun('This',
'''Can
Be
Multi''',
'line!'))
Result:
('This', 'Can\nBe\nMulti', 'line!')
Or:
def myFun(var1="""different""",var2="""quote""",var3='types'):
print (var1, var2, var3)
myFun('This',
'''Can
Be
Multi''',
'line!')
Result:
This Can
Be
Multi line!

From the docs:
String literals can be enclosed in matching single quotes (') or double quotes ("). They can also be enclosed in matching groups of three single or double quotes (these are generally referred to as triple-quoted strings). [...other rules applying identically to all string literal types omitted...]
In triple-quoted strings, unescaped newlines and quotes are allowed (and are retained), except that three unescaped quotes in a row terminate the string. (A “quote” is the character used to open the string, i.e. either ' or ".)
Thus, triple-quoted string literals can span multiple lines, and can contain literal quotes without use of escape sequences, but are otherwise exactly identical to string literals expressed with other quoting types (including those using escape sequences such as \n or \' to express the same content).
Also see the Python 3 documentation: Bytes and String Literals -- which expresses an effectively identical set of rules with slightly different verbiage.
A more gentle introduction is also available in the language tutorial, which explicitly introduces triple-quotes as a way to permit strings to span multiple lines:
String literals can span multiple lines. One way is using triple-quotes: """...""" or '''...'''. End of lines are automatically included in the string, but it’s possible to prevent this by adding a \ at the end of the line. The following example:
print("""\
Usage: thingy [OPTIONS]
-h Display this usage message
-H hostname Hostname to connect to
""")
produces the following output (note that the initial newline is not included):
Usage: thingy [OPTIONS]
-h Display this usage message
-H hostname Hostname to connect to
To be clear, though: These are different syntax, but the string literals they create are indistinguishable from each other. That is to say, given the following code:
s1 = '''foo
'bar'
baz
'''
s2 = 'foo\n\'bar\'\nbaz\n'
there's no possible way to tell s1 and s2 apart from each other by looking at their values: s1 == s2 is true, and so is repr(s1) == repr(s2). The Python interpreter is even allowed to intern them to the same value, so it may (or may not) make id(s1) == id(s2) true depending on details (such as whether the code was run at the REPL or imported as a module).

FWIW, my understanding is that there's a convention whereby """ """, ''' ''' are used for docstring, which is kinda like a #comment, but is a recallable attribute that can be referenced later. https://www.python.org/dev/peps/pep-0257/
I'm a beginner too, but my understanding is that using triple quotes for strings is not the best idea, even if there's little functional difference with what you're doing currently (I don't know if there might be later). Sticking with conventions is helpful to others reading and using your code, and it seems to be a good rule of thumb that some conventions will bite you if you don't follow them, as in this case where a mal-formatted string with triple quotes will be interpreted as a docstring, and maybe not throw an error, and you'll need to search through a bunch of code to find the issue.

How to open a file in its default program with python

I want to open a file in python 3.5 in its default application, specifically 'screen.txt' in Notepad.
I have searched the internet, and found os.startfile(path) on most of the answers. I tried that with the file's path os.startfile(C:\[directories n stuff]\screen.txt) but it returned an error saying 'unexpected character after line continuation character'. I tried it without the file's path, just the file's name but it still didn't work.
What does this error mean? I have never seen it before.
Please provide a solution for opening a .txt file that works.
EDIT: I am on Windows 7 on a restricted (school) computer.

It's hard to be certain from your question as it stands, but I bet your problem is backslashes.
[EDITED to add:] Or actually maybe it's something simpler. Did you put quotes around your pathname at all? If not, that will certainly not work -- but once you do, you will find that then you need the rest of what I've written below.
In a Windows filesystem, the backslash \ is the standard way to separate directories.
In a Python string literal, the backslash \ is used for putting things into the string that would otherwise be difficult to enter. For instance, if you are writing a single-quoted string and you want a single quote in it, you can do this: 'don\'t'. Or if you want a newline character, you can do this: 'First line.\nSecond line.'
So if you take a Windows pathname and plug it into Python like this:
os.startfile('C:\foo\bar\baz')
then the string actually passed to os.startfile will not contain those backslashes; it will contain a form-feed character (from the \f) and two backspace characters (from the \bs), which is not what you want at all.
You can deal with this in three ways.
You can use forward slashes instead of backslashes. Although Windows prefers backslashes in its user interface, forward slashes work too, and they don't have special meaning in Python string literals.
You can "escape" the backslashes: two backslashes in a row mean an actual backslash. os.startfile('C:\\foo\\bar\\baz')
You can use a "raw string literal". Put an r before the opening single or double quotes. This will make backslashes not get interpreted specially. os.startfile(r'C:\foo\bar\baz')
The last is maybe the nicest, except for one annoying quirk: backslash-quote is still special in a raw string literal so that you can still say 'don\'t', which means you can't end a raw string literal with a backslash.

The recommended way to open a file with the default program is os.startfile. You can do something a bit more manual using os.system or subprocess though:
os.system(r'start ' + path_to_file')
or
subprocess.Popen('{start} {path}'.format(
start='start', path=path_to_file), shell=True)
Of course, this won't work cross-platform, but it might be enough for your use case.

For example I created file "test file.txt" on my drive D: so file path is 'D:/test file.txt'
Now I can open it with associated program with that script:
import os
os.startfile('d:/test file.txt')

Escaping values for vim.command, vim.eval in Python vim plugins

I'm writing a python plugin for vim and it's looking like the only way to call a specific command is with the vim.command function. However, just substituting values into the function seems like a bad idea. How would I escape values so that I can pass untrusted data as an argument into a vim function? As a simple example, let's say I want to echo out untrusted input (I know I could just use print, but this is just an example). I would do something like:
value = get_data_from_untrusted_source()
vim.command("echo %s" % value)
However, if that untrusted data has a | in it, the command is ended and a new one is executed which is bad. Even if I use quotes, we end up with sql injection like attacks where an attacker can just put an apostrophe in their response to end the string. Then if we double quote, it could be possible to put a backslash somewhere to end the quote. For example if we just double quotes we would go from \' to \'' which escapes the first quote.
Basically what I'm asking is if there's a safe way to call vim functions from a python plugin and would appreciate any help.

How to programmatically escape quotes andd slashes

I need a python script to call a bash script on windows.
So basically I must make a subprocess call form python, that will call cygwin with the -c option that will call the script I need,
The problem is that this script takes a few arguments and that these arguments are full os spaces and quotes and slashes.
I'm using code like the following
arq_saida_unix = arq_saida.replace("\\","/")
subprocess.call("C:\\cygwin64\\bin\\bash \".\\retirarVirgula.sh\\ \""+arq_saida+"\"")
Or I'm directly escaping, which sometimes takes me to as much as 8 backslashes in a row, for a backslash to get to my script must be escaped i) in bash ii) in cmd.exe iii) in python
all of this is error prone and takes quite some time every time to get it right.
Is there a better way of doing it? Ideally I wouldn't have any escaping backslashes, but anything that avoids the triple-slash double quote above would be nice.
I tried to use re.escape, but could figure out how exactly to use it , except as a replacement to .replace("\","/") and similar.

Don't pass a single string to call; instead, pass a list consisting of the command name and one argument per element. This saves you from needing to protect special characters from shell interpretation.
subprocess.call(["retirarVirgula.sh", arq_saida], executable=r"C:\cygwin64\bin\bash")
Note: I'm assuming arq_saida contains the single argument to pass to the script; if the script takes multiple arguments, then arc_saida should probably be built as a list as well:
arq_saida = ["arg", "arg two", "arg three"]
subprocess.call(["retirarVirgula.sh"] + arq_saida, executable=r"C:\cygwin64\bin\bash")

python: SyntaxError: EOL while scanning string literal

I have the above-mentioned error in s1="some very long string............"
Does anyone know what I am doing wrong?

You are not putting a " before the end of the line.
Use """ if you want to do this:
""" a very long string ......
....that can span multiple lines
"""

I had this problem - I eventually worked out that the reason was that I'd included \ characters in the string. If you have any of these, "escape" them with \\ and it should work fine.

(Assuming you don't have/want line breaks in your string...)
How long is this string really?
I suspect there is a limit to how long a line read from a file or from the commandline can be, and because the end of the line gets choped off the parser sees something like s1="some very long string.......... (without an ending ") and thus throws a parsing error?
You can split long lines up in multiple lines by escaping linebreaks in your source like this:
s1="some very long string.....\
...\
...."

In my situation, I had \r\n in my single-quoted dictionary strings. I replaced all instances of \r with \\r and \n with \\n and it fixed my issue, properly returning escaped line breaks in the eval'ed dict.
ast.literal_eval(my_str.replace('\r','\\r').replace('\n','\\n'))
.....

I faced a similar problem. I had a string which contained path to a folder in Windows e.g. C:\Users\ The problem is that \ is an escape character and so in order to use it in strings you need to add one more \.
Incorrect: C:\Users\
Correct: C:\\Users\\

You can try this:
s = r'long\annoying\path'

I too had this problem, though there were answers here I want to an important point to this
after
/ there should not be empty spaces.Be Aware of it

I also had this exact error message, for me the problem was fixed by adding an " \"
It turns out that my long string, broken into about eight lines with " \" at the very end, was missing a " \" on one line.
Python IDLE didn't specify a line number that this error was on, but it red-highlighted a totally correct variable assignment statement, throwing me off. The actual misshapen string statement (multiple lines long with " \") was adjacent to the statement being highlighted. Maybe this will help someone else.

In my case, I use Windows so I have to use double quotes instead of single.
C:\Users\Dr. Printer>python -mtimeit -s"a = 0"
100000000 loops, best of 3: 0.011 usec per loop

In my case with Mac OS X, I had the following statement:
model.export_srcpkg(platform, toolchain, 'mymodel_pkg.zip', 'mymodel.dylib’)
I was getting the error:
File "<stdin>", line 1
model.export_srcpkg(platform, toolchain, 'mymodel_pkg.zip', 'mymodel.dylib’)
^
SyntaxError: EOL while scanning string literal
After I change to:
model.export_srcpkg(platform, toolchain, "mymodel_pkg.zip", "mymodel.dylib")
It worked...
David

In my case, I forgot (' or ") at the end of string. E.g 'ABC' or "ABC"

I was getting this error in postgresql function. I had a long SQL which I broke into multiple lines with \ for better readability. However, that was the problem. I removed all and made them in one line to fix the issue. I was using pgadmin III.

Your variable(s1) spans multiple lines. In order to do this (i.e you want your string to span multiple lines), you have to use triple quotes(""").
s1="""some very long
string............"""

In this case, three single quotations or three double quotations both will work!
For example:
"""Parameters:
...Type something.....
.....finishing statement"""
OR
'''Parameters:
...Type something.....
.....finishing statement'''

I had faced the same problem while accessing any hard drive directory.
Then I solved it in this way.
import os
os.startfile("D:\folder_name\file_name") #running shortcut
os.startfile("F:") #accessing directory
The picture above shows an error and resolved output.

All code below was tested with Python 3.8.3
Simplest -- just use triple quotes.
Either single:
long_string = '''some
very
long
string
............'''
or double:
long_string = """some
very
long
string
............"""
Note: triple quoted strings retain indentation, it means that
long_string = """some
very
long
string
............"""
and
long_string = """some
very
long
string
............"""
or even just
long_string = """
some
very
long
string
............"""
are not the same.
There is a textwrap.dedent function in standard library to deal with this, though working with it is out of question's scope.
You can, as well, use \n inside a string, residing on single line:
long_string = "some \nvery \nlong \nstring \n............"
Also, if you don't need any linefeeds (i.e. newlines) in your string, you can use \ inside regular string:
long_string = "some \
very \
long \
string \
............"

Most previous answers are correct and my answer is very similar to aaronasterling, you could also do 3 single quotations
s1='''some very long string............'''