Hello,
This subject comes around every now and again, but I can't find anything useful searching.
I'm calling a function, CRTM_Read_Atmosphere_Record(), like so:
Atm = PTRARR(n_Profiles)
FOR m = 0, n_Profiles-1 DO BEGIN
Atm[m] = PTR_NEW({CRTM_Atmosphere})
result = CRTM_Read_Atmosphere_Record( FileID, *Atm[m], DEBUG=Debug )
...check result....
ENDFOR
That function in turns calls another function, CRTM_Read_Cloud_Record(), like so:
FUNCTION CRTM_Read_Atmosphere_Record, FileID , $ ; Input
Atm , $ ; Output
DEBUG=Debug ; Optional input
.....
FOR n = 0, Atm.n_Clouds-1 DO BEGIN
result = CRTM_Read_Cloud_Record( FileID, (*Atm.Cloud)[n], DEBUG=Debug )
...check result....
ENDFOR
And inside the CRTM_Read_Cloud_Record() function I do the following:
FUNCTION CRTM_Read_Cloud_Record, FileID , $ ; Input
Cloud , $ ; Output
DEBUG=Debug ; Optional input
.....
Type = Cloud.Type
READU, FileID, Type, $
*Cloud.Effective_Radius, $
*Cloud.Effective_Variance, $
*Cloud.Water_Content
Cloud.Type = Type
(and similar for an Aerosol structure and I/O function. Also, assume the pointer component
allocation has been done to the correct array size))
As you have probably guessed, by the time I inspect all the data that is returned in the
original Atm pointer array, everything is fine *except* the cloud type flag. It is zero.
So, I realise this is one of those pass-by-reference or pass-by-value things, but how does
one get around it? Do I:
a) make the Type component of the Cloud structure a pointer? (Yuk!)
b) change the way I pass the Cloud structure into the CRTM_Read_Cloud_Record() fn?
i.e. not reference the cloud structure array via the index [n].
I would much prefer (b), but will that entail copying entire structures? The number of
"Clouds" associated with any particular "Atm[m]" profile is variable.
Thanks for any info.
cheers,
paulv
p.s. FWIW, the structure definitions are:
PRO CRTM_Atmosphere__Define
void = { CRTM_Atmosphere, $
n_Layers : 0L, $
n_Absorbers : 0L, $
n_Clouds : 0L, $
n_Aerosols : 0L, $
Climatology : 0L, $
Absorber_ID : PTR_NEW(), $
Absorber_Units : PTR_NEW(), $
Level_Pressure : PTR_NEW(), $
Pressure : PTR_NEW(), $
Temperature : PTR_NEW(), $
Absorber : PTR_NEW(), $
Cloud : PTR_NEW(), $
Aerosol : PTR_NEW() }
END
and
PRO CRTM_Cloud__Define
void = { CRTM_Cloud, $
n_Layers : 0L, $
Type : 0L, $
Effective_Radius : PTR_NEW(), $
Effective_Variance : PTR_NEW(), $
Water_Content : PTR_NEW() }
END
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