_tcontext.pyzdoc

Go to the documentation of this file.

\pythondoc TDirectory::TContext
 
The functionality offered by TContext can be used in PyROOT with a context manager. Here are a few examples:
\code{.py}
import ROOT
from ROOT import TDirectory
 
with TDirectory.TContext():
    # Open some file here
    file = ROOT.TFile(...)
    # Retrieve contents from the file
    histo = file.Get("myhisto")
 
# After the 'with' statement, the current directory is restored to ROOT.gROOT
\endcode
\n
\code{.py}
import ROOT
from ROOT import TDirectory
 
file1 = ROOT.TFile("file1.root", "recreate")
#...
file2 = ROOT.TFile("file2.root", "recreate")
#...
file3 = ROOT.TFile("file3.root", "recreate")
 
# Before the 'with' statement, the current directory is file3 (the last file opened)
with TDirectory.TContext(file1):
    # Inside the statement, the current directory is file1
    histo = ROOT.TH1F(...)
    histo.Write()
 
# After the statement, the current directory is restored to file3
\endcode
\n
\code{.py}
import ROOT
from ROOT import TDirectory
 
file1 = ROOT.TFile("file1.root")
file2 = ROOT.TFile("file2.root")
 
with TDirectory.TContext(file1, file2):
    # Manage content in file2
    histo = ROOT.TH1F(...)
    # histo will be written to file2
    histo.Write()
 
# Current directory is set to 'file1.root'
\endcode
 
Note that TContext restores the current directory to its status before the 'with'
statement, but does not change the status of any file that has been opened inside
the context (e.g. it does not automatically close the file).
 
\endpythondoc