I am trying to run a python script from ruby method. I am running this method as a rake task within a Rails app. I am using the solution mentioned here:
def create
path = File.expand_path('../../../../GetOrders', __FILE__)
output = `"python2 " + path + "/parse.py"`
print output
str = JSON.parse(output)
print str
end
EDIT: This works:
output = `python2 #{path}/parse.py`
EDIT2:
Using the python script i am trying to pass a list of dictionaries to the ruby function. The python script looks something like:
import xml.etree.ElementTree as ET
import json
def parse():
tree = ET.parse('response.xml')
root = tree.getroot()
namespaces = {'resp': 'urn:ebay:apis:eBLBaseComponents'}
order_array = root.find("resp:OrderArray", namespaces=namespaces)
detailsList = []
for condition:
details["key1"] = value1
details["key2"] = value2
detailsList.append(details)
output = json.dumps(detailsList)
return output
print parse()
Could someone explain what i am doing wrong and how can I fix this. Thanks
When you do this:
output = `python2 #{path}/parse.py`
output will be assigned the standard output of the python script, but that script isn't writing anything to standard output; the json data that's the return value of the parse() call is simply discarded. You seem to be expecting the execution of the script to have a "return value" that's the return value of the script's last expression, but that's not how processes work.
You probably want to replace the parse() call at the end of the script with print parse().
You are calling this exact line on the shell:
"python2 -path- /parse.py"
which the shell interprets as a single command: python2 (with a space at the end).
Try using string interpolation, which works with the backtick operator:
output = `python2 #{path}/parse.py`
Imagine typing this exact string:
"python2 " + path + "/parse.py"
into your shell (e.g. bash). It would look for a program named "python2 " and give it four arguments
+
path
+
/parse.y
You can't put arbitrary Ruby code inside a backtick string the same way you can't put arbitrary code in normals strings. You must use string interpolation.
Related
I have the following code:
dofile(arg[1])
function1 = arg[2]
argument = arg[3]
returned = _G[function1](argument)
print(returned)
It is designed to take three command-line arguments and run a function from a file.
So, i run the command lua libs.lua "printStuff.lua" "printStuff" "\"Hello, World\"", and i always end up with this:
"Hello, World"
nil
I don't understand why i always get "nil".
Here are the contents of printstuff.lua:
function printStuff(stuff)
print(stuff)
end
That is to be expected. What's going on here:
You're executing the file specified by the first argument, printstuff.lua, which will leave a function printStuff in the global table _G.
You're indexing the global table with the second argument, printStuff, obtaining that function
You're calling the function you just obtained with the third command line argument, "Hello World!", as parameter, which prints it, and storing the result of that in the global variable returned. The function printStuff doesn't return anything (there's no return in there, and even if there was, print doesn't return anything either), so you're assigning nil to returned.
You're printing returned, which is nil
Side note: I'd use the vararg ... instead of the arg table for improved readability:
local file, func, param = ...
dofile(file); print(func(param))
Why not simply...
-- xlua.lua
-- Example: lua xlua.lua os date "%H:%M:%S"
-- Or: lua xlua.lua _G print "Hello World"
-- Or: lua xlua.lua dofile /path/to/someusefull.lua "Arg for someusefull.lua"
local result = _G[arg[1]][arg[2]](arg[3])
-- 5. Only put out whats not nil
if (result ~= nil) then
print(result)
end
def a = "a string"
def b = 'another'
Is there any difference? Or just like javascript to let's input ' and " easier in strings?
Single quotes are a standard java String
Double quotes are a templatable String, which will either return a GString if it is templated, or else a standard Java String. For example:
println 'hi'.class.name // prints java.lang.String
println "hi".class.name // prints java.lang.String
def a = 'Freewind'
println "hi $a" // prints "hi Freewind"
println "hi $a".class.name // prints org.codehaus.groovy.runtime.GStringImpl
If you try templating with single quoted strings, it doesn't do anything, so:
println 'hi $a' // prints "hi $a"
Also, the link given by julx in their answer is worth reading (esp. the part about GStrings not being Strings about 2/3 of the way down.
My understanding is that double-quoted string may contain embedded references to variables and other expressions. For example: "Hello $name", "Hello ${some-expression-here}". In this case a GString will be instantiated instead of a regular String. On the other hand single-quoted strings do not support this syntax and always result in a plain String. More on the topic here:
http://docs.groovy-lang.org/latest/html/documentation/index.html#all-strings
I know this is a very old question, but I wanted to add a caveat.
While it is correct that single (or triple single) quotes prevent interpolation in groovy, if you pass a shell command a single quoted string, the shell will perform parameter substitution, if the variable is an environment variable. Local variables or params will yield a bad substitution.
what is wrong with below code, comparing 2 strings in groovy
I am trying do the comparison between the 2 parameters in a single line to make it look tidier
if (params.dirname == ((params.path =~ ~/${params.dirname}/).with { matches() ? it[0] : null })) {
print success
}
Throwing Exception -
java.lang.NoSuchMethodError: No such DSL method 'matches' found among steps
There is no need to over-complicate your use case. According to:
params.dirname = hde, params.path = /usr/tmp/jenkins/hde/filename.txt or /usr/hde/jenkins/ing/filename.txt or any random path which has hde in it
you are trying to find if given string a contains substring b. It can be done using Java's method String.contains(String substring). Alternatively you can use regular expression for that, but String.contains() just looks a few times simpler to understand what is your intention. Consider following Groovy script:
def params = [
dirname: 'hde',
path: '/usr/tmp/jenkins/hde/filename.txt'
]
// Using String.contains()
if (params.path.contains(params.dirname)) {
println "Path '${params.path}' contains '${params.dirname}'"
}
// Using regular expression
if (params.path ==~ /(.*)${params.dirname}(.*)/) {
println "Path '${params.path}' contains '${params.dirname}'"
}
When you run it both if statements evaluates to true:
Path '/usr/tmp/jenkins/hde/filename.txt' contains 'hde'
Path '/usr/tmp/jenkins/hde/filename.txt' contains 'hde'
I am writing a Lua 5.3 program and it requires arguments to be passed to it. I use the arg table to get the first argument: arg[1], but the 1st argument, according to the script, is nil even though I have passed an argument to the file.
Here's the code that I've written:
local strin = arg[1]:sub(2,arg[1]:len()-1) -- to remove the quote marks
local i = 0
for W in strin:gmatch(".") do
i = i + 1
if W == " " or W == "\t" then strin = strin:sub(i+1) else break end
end
print(strin)
I pass the argument to the file like this:
C:\Users\WhiteKid\Documents\Scripts>RemoveWhiteSpace.lua " hello world!"
It thinks arg[1] is a nil value when it is not. Is there a different way of getting the arguments passed to a lua script in Lua 5.3?
Since you are calling the .lua script directly (C:\Users\WhiteKid\Documents\Scripts>RemoveWhiteSpace.lua " hello world!"), you seem to have an association with a lua interpreter. You need to make sure you pass %1 or %* to the interpreter you are calling in that association. Alternatively, try calling the Lua interpreter and passing the script name and the parameters and it should work as you expect.
Also, you should check if arg[1] is present and check if the quotes are also there (as they may be removed before the parameters get to the script, so you should not always expect them).
I tried the utility method provided by luaj to call a lua file with command line args (this one http://lua-users.org/wiki/SourceCodeFormatter)
Globals globals = JsePlatform.standardGlobals();
String script ="src/codeformatter.lua";
File f = new File(script);
LuaValue chunk = globals.loadfile(f.getCanonicalPath());
List<String> argList = Arrays.asList("--file","test.lua");
JsePlatform.luaMain(chunk, argList.toArray(new String[argList.size()]));
However i always get attempt to call nil where the code tries to access the arg table ( while i < table.getn(arg) do) - i tried other examples and they all result in the same error - luaj does not seem to set the "arg" table correctly - even a simply print arg[1] will not work.
LuaJ does not support table.getn anymore because it got removed in lua 5.1 - replace every occurances of table.getn with #varname - and init the args array with ocal args={...} at the top made it work.
Still, the code formatter does not really do what i expected it todo
There are two issues:
calls to table.getn(arg) should be replaced with #arg
the chunk's environment is not set up properly by luaj 3.0.1 so arg isn't set
However, as a workaround, you can capture the inputs using the varargs "..." syntax by adding a line at the top of codeformatter.lua such as
arg = {...}
Here is a code snippet to illustrate:
Globals globals = JsePlatform.standardGlobals();
LuaValue chunk = globals.load(
"arg = {...};" +
"print(#arg, arg[1], arg[2])");
JsePlatform.luaMain(chunk, new String[] {"--file","test.lua"});
Produces output:
2 --file test.lua