TypeError: Can't convert 'int' object to str implicitly

Discussion in 'Python' started by tunacubes, Apr 26, 2013.

  1. tunacubes

    tunacubes Guest

    Hey,

    Let me explain what my program is supposed to do...

    I am using a macro program in conjunction with a python script I am writing.. The macro inputs data into a database we use at my job, blah blah blah.

    The script asks how many numbers (devices) you need to enter. Next, it asksyou to input the device numbers. When you input them, it creates a list with all of the devices. I then tell it to go into the script of the Macro (firstdev.ahk) that will run on the back-end, and replace the word "device" with the first device in the list. It then should execute the Macro, change the device number back to the word "Device" for future use, and then deletethe first number from the list. It will repeat as long as there are numbers in the list.

    The error I receive is "TypeError: Can't convert 'int' object to str implicitly" when it tries to put the device into the macro script. It worked finewhen I just had it input one device into the script without the use of lists, but for whatever reason, using a list does not play nice with replacingthe words "Device" with the number from the list. Here is my script. I will give you up until the part that the error occurs, as everything afterwords is pointless.

    I am fairly new to python, so if anything looks screwed up or like I am an idiot, it is because I am.

    import fileinput, sys, os
    devlist = []
    maxdev = int(input("How many devices to add: "))
    curdev = int("0")
    while curdev < maxdev:
    try:
    Number = int(input("Enter Device number: "))
    devlist.append(Number)
    curdev = curdev + 1
    except ValueError:
    print("Please enter a valid number")
    ready = 0
    while ready != "Y" and ready != "y" and ready != "yes" and ready !="YES" and ready != "ready" and ready != "Ready":
    try:
    ready = input("Confirm when you are ready ")
    except ValueError:
    print("shit broke. ")
    ##This next step will seek out the word Device within firstdev.ahk, and replace with devlist[0]
    for line in fileinput.input(["firstdev.ahk"], inplace=True):
    line = line.replace("device", devlist[0])
    sys.stdout.write(line)
    ##next step runs firstdev.ahk
    os.system('firstdev.ahk')
    ##next step is replacing devlist[0] with "device"
    for line in fileinput.input(["firstdev.ahk"], inplace=True):
    line = line.replace(devlist[0], "device")
    sys.stdout.write(line)
    del devlist[0] #deleting the first item from the list. next steps will repeat.


    Thanks in advance.
     
    tunacubes, Apr 26, 2013
    #1
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  2. tunacubes

    Peter Otten Guest

    Python is trying hard to give you a meaningful error message and shows the
    line causing the error in the traceback. It pays to read carefully -- or to
    post it here if it doesn't make sense to you.
    devList is a list of integers, and devlist[0] is thus an int.
    Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
    TypeError: Can't convert 'int' object to str implicitly

    Implicitly? So let's try and convert the int /explicitly/ .
    'foo device bar\n'

    No error, but probably still not what you expected. Can you sort it out
    yourself?
    I like to see a bit of self-deprecation now and then, but on this list
    complete tracebacks find even more love ;)
     
    Peter Otten, Apr 26, 2013
    #2
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  3. Welcome to Python. One thing that you'll quickly learn is that the
    full traceback is REALLY helpful; in this case, there won't be much
    traceback, but at least you'll get the line number. I'm looking at
    this line as being the culprit:
    All you need to do is convert that to a string:
    line = line.replace("device", str(devlist[0]))
    and that should fix your problem. But while I'm here, may I offer a
    few other tips?

    (By the way, I'm going to assume you're using Python 3 here, because
    otherwise your "confirm when ready" would be bombing. But it helps to
    say what version you're using.)
    Just 'curdev = 0' would work here. No need to convert a string to an
    integer - just use a literal integer.
    UI suggestion: Let the user keep on inputting device numbers until
    some kind of sentinel (eg a blank line), unless it makes really good
    sense to ask for the number up-front.
    You can save the hassle of maintaining curdev by simply looking at
    len(devlist) - that is, change your condition to "while len(devlist) <
    maxdev".
    Here's a really cool tip. You can simply check set membership:

    while ready not in {"Y","y","yes","YES","ready","Ready"}:

    But I'd be inclined to make the UI a bit tighter here and make it
    something like:

    ready = input("Confirm when you are ready <y/N>: ")

    and then just look for either "Y" or "y", nothing more. But that's up
    to you. You know who's going to use this program, I don't. (The
    capitalized N representing that the default is No is a convention you
    may or may not want to follow.)
    Drop the try/except; if there's something wrong (and, btw, I'm not
    sure what circumstances would trigger a ValueError here - maybe
    someone else knows of something?), just let the exception terminate
    the program. There's nothing useful to do here anyway :)
    You're reading a single file with constant name here. Save yourself
    some trouble: just open the file directly.

    for line in open("firstdev.ahk"):
    print(line.replace("device", str(devlist[0])))

    Though I'm not sure why you want to write to stdout here. Were you
    intending to write back to another file? I'm getting a bit lost in
    your code here. My understanding of your intentions, from your
    comments, is that you actually want to repeat most of the code from
    here on for each device number entered - that strongly suggests a
    'for' loop bracketing the whole thing. Is that what you meant this to
    do? Currently, it'll get to the 'del' at the bottom, and then just
    terminate.
    And here you repeat everything from above. Again, not sure what you're
    intending to do here.
    The steps won't repeat by themselves, so this is where I'm thinking
    you actually want a for loop.

    I hope you don't take this the wrong way, as I feel now (on skimming
    over this email prior to sending) that I've kinda pulled your code to
    pieces a bit! It's just advice, just suggestions; this is your code
    and nobody else's. You may very well disagree with any or all of what
    I've said, and that's to be expected. It's also a great way to get
    discussion going, and discussion is one of the best ways for everyone
    to learn :)

    Chris Angelico
     
    Chris Angelico, Apr 26, 2013
    #3
  4. I've checked out what fileinput.input() is doing here (ought to have
    done that earlier, sorry!) and I now understand this block of code
    more. You're replacing that word _in the file, on disk_, and then
    making the inverse replacement. This strikes me as dangerous; if
    anything happens to your process in the middle, the file will be
    damaged on disk. I would STRONGLY recommend rewriting this to use some
    other file - for instance, a temporary file. I haven't looked into the
    details, as I haven't actually done this lately in Python, but you
    should be able to use tempfile.NamedTemporaryFile(delete=False) [1],
    write to it, make it executable, run it, and unlink it. That way,
    you're creating a temporary file to run, not running the original.
    This is semantically different from your code, but I think it'd be a
    lot safer.

    [1] http://docs.python.org/3.3/library/tempfile.html#tempfile.NamedTemporaryFile

    ChrisA
     
    Chris Angelico, Apr 26, 2013
    #4
  5. tunacubes

    tunacubes Guest

    Thank you, Peter. This was a tremendous help. Got it working.
     
    tunacubes, Apr 26, 2013
    #5
  6. tunacubes

    tunacubes Guest

    Thank you, Chris! I got it working and am going to take your advice on the tempfile idea. I actually ran into the problem you were referring to, and kept the .ahk files backed up elsewhere for when this situation arose. I appreciate the help!
     
    tunacubes, Apr 26, 2013
    #6
  7. Awesome!

    Hey, you want to know an easy way to show your appreciation for the
    people who answer your questions? It's really simple:

    Step 1: Don't use Google Groups to post.
    Step 2: Profit!

    Have a look at the quoted text in your responses. See how it's
    double-spaced and really obnoxious? That's not your fault, it's
    because Google Groups is buggy. There are plenty of other ways to read
    and post; I personally have subscribed to the mailing list and read it
    using Gmail, and there are a variety of other ways too. If you _must_
    use Google Groups, check out this page for some recommendations on how
    to not offend people.

    http://wiki.python.org/moin/GoogleGroupsPython

    There are a number of non-G-rated terms going around that fairly
    accurately describe what Google Groups posts look like, but since I
    prefer milder language, I'll just repeat the word "obnoxious", as it
    carries all the meaning I need.

    ChrisA
     
    Chris Angelico, Apr 26, 2013
    #7
  8. tunacubes

    Dave Angel Guest

    fileinput.Fileinput class already creates the temp file when you specify
    inplace=True

    If it didn't, I'd also have to point out the hazards of doing in-place
    updates in a text file where the new data and old is a different length.

    There still may be reasons to make an explicit backup, but I don't know
    what they are.
     
    Dave Angel, Apr 26, 2013
    #8
  9. That's true if something goes wrong during the actual writing of the
    file only. But if the process bombs in the middle of the execution
    phase (which in the Python script is a single os.system() call), then
    the file will have been one-way changed on the disk - hence,
    "damaged". The explicit temporary file (and executing the temp file)
    is a much safer way to do it.

    ChrisA
     
    Chris Angelico, Apr 26, 2013
    #9
  10. tunacubes

    Dave Angel Guest

    Only two of those sentences makes sense to me. I have no idea what
    "execution phase" means, and don't know what would be done via an
    os.system() call. I don't know what "one-way change" means

    If I were specifying the fileinput stuff, I'd have said the new data
    should be written to the temp file, so that at no time was the original
    file in an in-between state.
     
    Dave Angel, Apr 26, 2013
    #10
  11. Here's a massive simplification of the OP's program:

    1. Build a list of device IDs
    2. Edit the file "firstdev.ahk" and replace all instances of "device"
    with the device ID
    3. Execute the now-edited firstdev.ahk using os.system()
    4. Reverse the edit of firstdev.ahk, replacing all instances of the
    device ID with the word "device".

    Apart from the risk of accidentally changing back something that
    wasn't changed in the first place (which the OP may know to be
    impossible, eg if the macro file has no numbers in it), this has the
    risk that a computer failure in step 3 will leave the file on disk in
    its edited state. That's what I'm concerned about. By writing the
    modified .ahk content to a different file and then executing the other
    file, he would avoid editing the template at all. It'd also then be
    multi-process safe, for what that's worth.

    ChrisA
     
    Chris Angelico, Apr 26, 2013
    #11
  12. tunacubes

    Dave Angel Guest

    OK, thanks. That makes perfect sense. Somehow I missed that it was the
    altered file that was being used as a script. I just assumed it was
    like a config file for some program, where the name is hardwired.
     
    Dave Angel, Apr 26, 2013
    #12
  13. tunacubes

    delonbest

    Joined:
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    The TypeError: can't convert 'int' object to str implicitly is generated because '+' (addition) does not work between an integer and a string. When concatenating strings with integers - you can't directly stick together a string and an integer. So, in order to resolve this problem, you have to explicitly parse the integer to a string by the str() built-in function string + str(number) or use formatting to format your output.
     
    delonbest, Mar 9, 2020
    #13
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