help regarding syntax

[Giuseppe:G:]

Hi, any idea on what is this code doing:

//=============== =============== ===
1 #include <boost/scoped_ptr.hpp>

....

3 typedef std::vector<std ::vector<pair<s ize_t, size_t ParamsType;

5 /*
6 *Is the following a boost shared pointer to a "ParamsType " object?
7 */
8 shared_ptr<Para msType>& params;

....
14 params.reset(ne w ParamsType(m_pr ed_map->size()));
15 for (size_t pid = 0; pid < m_pred_map->size(); ++pid) {
16 vector<pair<siz e_t, size_t& param = (*params)[pid]; // ??
...
}
//=============== =============== ===

I have problems with lines 14 & 16. First of all, is ParamsType a vector
of vectors of pairs? Then I think params is a pointer to that. Then, we
probably instantiate a new ParamsType and let params point at it. Right?

But then, what's happening in line 16?
Thanks in advance

Giuseppe

[Giuseppe:G:]

Anybody? please.. :) Is

vector<pair<siz e_t, size_t& param = (*params)[pid];

a kind of cast?

cheers
Giuseppe
Giuseppe:G: wrote:

Hi, any idea on what is this code doing:

//=============== =============== ===
1 #include <boost/scoped_ptr.hpp>

...

3 typedef std::vector<std ::vector<pair<s ize_t, size_t ParamsType;

5 /*
6 *Is the following a boost shared pointer to a "ParamsType " object?
7 */
8 shared_ptr<Para msType>& params;

...
14 params.reset(ne w ParamsType(m_pr ed_map->size()));
15 for (size_t pid = 0; pid < m_pred_map->size(); ++pid) {
16 vector<pair<siz e_t, size_t& param = (*params)[pid]; // ??
...
}
//=============== =============== ===

I have problems with lines 14 & 16. First of all, is ParamsType a vector
of vectors of pairs? Then I think params is a pointer to that. Then, we
probably instantiate a new ParamsType and let params point at it. Right?

But then, what's happening in line 16?
Thanks in advance

Giuseppe

[joseph cook]

On Jul 6, 6:30*pm, Giuseppe:G: <lone.nt...@SPA Mlibero.itwrote :

Anybody? please.. :) Is

vector<pair<siz e_t, size_t& param = (*params)[pid];

a kind of cast?

cheers
Giuseppe

Giuseppe:G: wrote:

Hi, any idea on what is this code doing:

//=============== =============== ===
1 #include <boost/scoped_ptr.hpp>

...

3 typedef std::vector<std ::vector<pair<s ize_t, size_t ParamsType;

5 /*
6 *Is the following a boost shared pointer to a "ParamsType " object?
7 */
8 shared_ptr<Para msType>& params;

...
14 params.reset(ne w ParamsType(m_pr ed_map->size()));
15 for (size_t pid = 0; pid < m_pred_map->size(); ++pid) {
16 * * * vector<pair<siz e_t, size_t& param = (*params)[pid];// ??
* * ...
}
//=============== =============== ===

I have problems with lines 14 & 16. First of all, is ParamsType a vector
of vectors of pairs? Then I think params is a pointer to that. Then, we
probably instantiate a new ParamsType and let params point at it. Right?

But then, what's happening in line 16?

If you think of it as a 2D matrix of "pair" objects, then this loop is
getting each "row" of of the matrix. The term "param" in most cases
would be used as a reference, because it is easier to read/type than
repeating "(*params)[pid]" everywhere else in the loop. It is just an
alias.

hth,
Joe Cook

[Giuseppe:G:]

Thanks Joe! Now I get it. It's as if we're "isolating" single rows ( or
columns) and then managing them through param.

Regards
Giuseppe

joseph cook wrote:

If you think of it as a 2D matrix of "pair" objects, then this loop is
getting each "row" of of the matrix. The term "param" in most cases
would be used as a reference, because it is easier to read/type than
repeating "(*params)[pid]" everywhere else in the loop. It is just an
alias.

hth,
Joe Cook