Basic string formatting with NIM - nim-lang

I am trying to do some very basic string formatting and I got immediately stuck.
What is wrong with this code?
import strutils
import parseopt2
for kind, key, val in getopt():
echo "$1 $2 $3" % [kind, key, val]
I get Error: type mismatch: got (TaintedString) but expected 'CmdLineKind = enum' but I don't understand how shall I fix it.

The problem here is that Nim's formatting operator % expects an array of objects with the same type. Since the first element of the array here has the CmdLineKind enum type, the compiler expects the rest of the elements to have the same type. Obviously, what you really want is all of the elements to have the string type and you can enforce this by explicitly converting the first paramter to string (with the $ operator).
import strutils
import parseopt2
for kind, key, val in getopt():
echo "$1 $2 $3" % [$kind, key, val]
In case, you are also wondering what is this TaintedString type appearing in the error message, this is a special type indicating a non-validated external input to the program. Since non-validated input data poses a security risk, the language supports a special "taint mode", which helps you keep track of where the inputs may need validation. This mode is inspired by a similar set of features available in the Perl programming language:
http://docstore.mik.ua/orelly/linux/cgi/ch08_04.htm

If you use the strformat Nim-inbuilt library, the same code snippet can be more concise:
import parseopt # parseopt2 has been deprecated!
import strformat
for kind, key, val in getopt():
echo fmt"{kind} {key} {val}"
Also note that parseopt replaces the deprecated parseopt2 library, at least as of today on Nim 0.19.2.

Related

How do I see a user-friendly format when debugging chrono::DateTime in vscode-lldb?

The debugger shows this for DateTime structs:
After looking at the docs for lldb to see how to format it, I see I can format integers as hex:
type format add -f hex i32
I tried something similar for DateTime
type format add --format hex chrono::datetime::DateTime<chrono::offset::utc::Utc>
It's not picking up the chrono type even though frame variable shows this as the type. Even after this step is done, not sure how to parse the date to string.
Using #Jim Ingham hints in the other answer and a touchup to this formula
Modify the launch.json file by adding
"initCommands": [
"command source '${workspaceFolder}/my_type_formatters'"
]
Add the following file called my_type_formatters to the root of the project.
command script import simd.py
type summary add -F simd.GetSummary chrono::datetime::DateTime<chrono::offset::utc::Utc>
Add a simd.py file to the root of the project with:
from datetime import datetime,timedelta
def GetSummary(valobj, internal_dict):
ymdf = valobj.GetChildMemberWithName('datetime').GetChildMemberWithName('date').GetChildMemberWithName('ymdf').GetValue();
secs = valobj.GetChildMemberWithName('datetime').GetChildMemberWithName('time').GetChildMemberWithName('secs').GetValue();
year = int(ymdf) >> 13
day_of_year = (int(ymdf) & 8191) >> 4;
date = datetime(year -1, 12, 31) + timedelta(days=day_of_year) + timedelta(seconds=int(secs))
return date.strftime('%Y-%m-%d %H:%M:%S')
Result:
lldb has three stages of customization for printing values of a given type. The simplest is "type format" which specifies the format to use (hex, chars, etc) to display scalar entities. The second is "type summary" which allows you to print a one-line string summary of the value. The third is "type synthetic" which allows you to present a value as some kind of structured object (e.g. making std::vector look like an vector of values rather than its internal form.)
You want to add a "type summary" for this type that parses the data and prints it as a human-readable string.

detect_langs how to use the output

I'm using the langdetect and it should return the probability/percentage of a certain language in a string which is something like [en:0.9999960343803843] for an English text. I want to check the language and the percentage and store them in variables to use them later but I can't do anything with it except printing it. the type seems to be <class 'langdetect.language.Language'>
lan="Otec matka syn."
lan=detect_langs(line)
print(lan)
print(type(lan[0]))
this code outputs
[pl:0.7142846922445223, fi:0.2857135474194883]
<class 'langdetect.language.Language'>
note: It's not json because i've tried json.loads(lan[0]) and an error says it should be a string not language
edit: as user696969 answered the solution was to save them in a dict
x=detect_langs(line)
lan={}
for lang in x:
lan.update({lang.lang: lang.prob})
Since they are language.Language object, you can convert each language data into dict type using the following code
from langdetect import detect_langs
line="Otec matka syn."
lan=[{lang.lang: lang.prob} for lang in detect_langs(line)]
print(lan)
print(type(lan[0]))
The expected output for lan would be
[{'fi': 0.8571392823357673}, {'pl': 0.14285943305652865}]
You can also store the entire list of languages into dictionary by replacing
lan=[{lang.lang: lang.prob} for lang in detect_langs(line)]
with
lan={lang.lang: lang.prob for lang in detect_langs(line)}
The expected output would be something like below
{'fi': 0.7142848220971209, 'pl': 0.2857147054811151}

Is it possible to do lazy formatting of a python string? [duplicate]

I want to use f-string with my string variable, not with string defined with a string literal, "...".
Here is my code:
name=["deep","mahesh","nirbhay"]
user_input = r"certi_{element}" # this string I ask from user
for element in name:
print(f"{user_input}")
This code gives output:
certi_{element}
certi_{element}
certi_{element}
But I want:
certi_{deep}
certi_{mahesh}
certi_{nirbhay}
How can I do this?
f"..." strings are great when interpolating expression results into a literal, but you don't have a literal, you have a template string in a separate variable.
You can use str.format() to apply values to that template:
name=["deep","mahesh","nirbhay"]
user_input = "certi_{element}" # this string i ask from user
for value in name:
print(user_input.format(element=value))
String formatting placeholders that use names (such as {element}) are not variables. You assign a value for each name in the keyword arguments of the str.format() call instead. In the above example, element=value passes in the value of the value variable to fill in the placeholder with the element.
Unlike f-strings, the {...} placeholders are not expressions and you can't use arbitrary Python expressions in the template. This is a good thing, you wouldn't want end-users to be able to execute arbitrary Python code in your program. See the Format String Syntax documenation for details.
You can pass in any number of names; the string template doesn't have to use any of them. If you combine str.format() with the **mapping call convention, you can use any dictionary as the source of values:
template_values = {
'name': 'Ford Prefect',
'number': 42,
'company': 'Sirius Cybernetics Corporation',
'element': 'Improbability Drive',
}
print(user_input.format(**template_values)
The above would let a user use any of the names in template_values in their template, any number of times they like.
While you can use locals() and globals() to produce dictionaries mapping variable names to values, I'd not recommend that approach. Use a dedicated namespace like the above to limit what names are available, and document those names for your end-users.
If you define:
def fstr(template):
return eval(f"f'{template}'")
Then you can do:
name=["deep","mahesh","nirbhay"]
user_input = r"certi_{element}" # this string i ask from user
for element in name:
print(fstr(user_input))
Which gives as output:
certi_deep
certi_mahesh
certi_nirbhay
But be aware that users can use expressions in the template, like e.g.:
import os # assume you have used os somewhere
user_input = r"certi_{os.environ}"
for element in name:
print(fstr(user_input))
You definitely don't want this!
Therefore, a much safer option is to define:
def fstr(template, **kwargs):
return eval(f"f'{template}'", kwargs)
Arbitrary code is no longer possible, but users can still use string expressions like:
user_input = r"certi_{element.upper()*2}"
for element in name:
print(fstr(user_input, element=element))
Gives as output:
certi_DEEPDEEP
certi_MAHESHMAHESH
certi_NIRBHAYNIRBHAY
Which may be desired in some cases.
If you want the user to have access to your namespace, you can do that, but the consequences are entirely on you. Instead of using f-strings, you can use the format method to interpolate dynamically, with a very similar syntax.
If you want the user to have access to only a small number of specific variables, you can do something like
name=["deep", "mahesh", "nirbhay"]
user_input = "certi_{element}" # this string i ask from user
for element in name:
my_str = user_input.format(element=element)
print(f"{my_str}")
You can of course rename the key that the user inputs vs the variable name that you use:
my_str = user_input.format(element=some_other_variable)
And you can just go and let the user have access to your whole namespace (or at least most of it). Please don't do this, but be aware that you can:
my_str = user_input.format(**locals(), **globals())
The reason that I went with print(f'{my_str}') instead of print(my_str) is to avoid the situation where literal braces get treated as further, erroneous expansions. For example, user_input = 'certi_{{{element}}}'
I was looking for something similar with your problem.
I came across this other question's answer: https://stackoverflow.com/a/54780825/7381826
Using that idea, I tweaked your code:
user_input = r"certi_"
for element in name:
print(f"{user_input}{element}")
And I got this result:
certi_deep
certi_mahesh
certi_nirbhay
If you would rather stick to the layout in the question, then this final edit did the trick:
for element in name:
print(f"{user_input}" "{" f"{element}" "}")
Reading the security concerns of all other questions, I don't think this alternative has serious security risks because it does not define a new function with eval().
I am no security expert so please do correct me if I am wrong.
This is what you’re looking for. Just change the last line of your original code:
name=["deep","mahesh","nirbhay"]
user_input = "certi_{element}" # this string I ask from user
for element in name:
print(eval("f'" + f"{user_input}" + "'"))

what is the workaround for QString.contains() method for pyqt4+python3?

I have been converting a Qt/C++ widget code into PyQt4+Python3. I have a QFileSystemModel defined and the items it returns have "data" with the filename as type "str". (This is of type QString in Qt/C++ or Python2x).
I have to search for a filter based on QRegEx. In Qt/C++ and Python2x this is achieved by QString.contains(QRegEx).
I found that QString has been removed in Python3. Since now in Python3 everything is now of type "str", how can i implement the old method QString.contains(QRegEx)?
Thanks,
Kodanda
For string mainipulation, Python is generally superior to anything Qt has to offer (particularly when it comes to regular expressions).
But if you must use QRegExp:
# test whether string contains pattern
if QRegExp(pattern).indexIn(string) != -1:
print('found')
Python:
if re.search(pattern, string):
print('found')

Unpredictable behaviour of scala triple quoted string

I'm using junit in scala to compare string output from my scala code. Something like :
val expected = """<Destination id="0" type="EMAIL">
<Address>
me#test.com
</Address>
<TimeZone>
US/Eastern
</TimeZone>
<Message>
</Message>
</Destination>
"""
val actual = getTextToLog()
info(" actual = " + actual)
assert(expected == actual)
The issue is that for some strings, assertions like :
assert(expected == actual)
work and for some they strings they dont. Even when I copy actual (logged to Eclipse console) from Eclipse console and paste it into expected just to be sure , the assertion still fails.
What am I missing?
OK, since this turns out to be a whitespace issues, you should sanitise the two strings before comparing them. Look at the RichString methods like .lines, for example, which might let you create a line-ending or whitespace-agnostic comparison method.
Here is one naive way of doing this with implicit conversions:
import scala.language.implicitConversions
object WhiteSpace {
implicit def strToWhiteSpace(s: String) = new WhiteSpace(s)
}
class WhiteSpace(val s: String) {
def `~==` (other: String) = s.lines.toList == other.lines.toList
}
which allows
import WhiteSpace._
assert(expected ~== actual)
Or you could extend the appropriate jutils class to add an agnostic version of assertEquals.
Note that this comparison deconstructs both strings in the same way. This is much safer than sending one of them on a round-trip conversion.
Whitespace/crlf issues are so common that there's no point fighting it by trying to stop the mismatches; just do agnostic comparisons.

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